2005-04-16 15:20:36 -07:00
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2015-02-05 16:27:35 +08:00
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2005-04-16 15:20:36 -07:00
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2015-02-05 16:27:35 +08:00
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2014-06-15 08:42:19 +08:00
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2005-04-16 15:20:36 -07:00
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2008-09-25 21:00:31 +04:00
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2008-01-23 22:34:09 -05:00
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2017-05-20 20:38:13 +02:00
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2008-01-23 22:34:09 -05:00
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2005-04-16 15:20:36 -07:00
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2005-03-19 01:10:05 -05:00
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2007-05-29 16:43:02 +04:00
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2008-09-25 21:00:31 +04:00
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include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 17:04:11 +09:00
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2013-12-03 08:49:16 +08:00
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2009-07-06 23:40:19 -04:00
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2013-12-03 08:49:16 +08:00
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2005-04-16 15:20:36 -07:00
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2010-07-16 13:11:31 +02:00
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2005-04-16 15:20:36 -07:00
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2007-05-29 16:43:02 +04:00
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2006-09-26 19:50:33 +04:00
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2005-04-16 15:20:36 -07:00
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2014-06-15 08:42:42 +08:00
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2005-03-19 01:10:05 -05:00
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2005-04-16 15:20:36 -07:00
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2007-05-29 16:42:57 +04:00
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2015-06-11 13:21:38 +08:00
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2006-09-26 19:50:33 +04:00
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2006-12-07 18:42:17 +03:00
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2006-12-07 18:42:17 +03:00
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2006-12-07 18:42:17 +03:00
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2007-05-29 16:43:02 +04:00
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2006-12-07 18:42:16 +03:00
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2006-09-26 19:50:33 +04:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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ACPI / EC: Clear stale EC events on Samsung systems
A number of Samsung notebooks (530Uxx/535Uxx/540Uxx/550Pxx/900Xxx/etc)
continue to log events during sleep (lid open/close, AC plug/unplug,
battery level change), which accumulate in the EC until a buffer fills.
After the buffer is full (tests suggest it holds 8 events), GPEs stop
being triggered for new events. This state persists on wake or even on
power cycle, and prevents new events from being registered until the EC
is manually polled.
This is the root cause of a number of bugs, including AC not being
detected properly, lid close not triggering suspend, and low ambient
light not triggering the keyboard backlight. The bug also seemed to be
responsible for performance issues on at least one user's machine.
Juan Manuel Cabo found the cause of bug and the workaround of polling
the EC manually on wake.
The loop which clears the stale events is based on an earlier patch by
Lan Tianyu (see referenced attachment).
This patch:
- Adds a function acpi_ec_clear() which polls the EC for stale _Q
events at most ACPI_EC_CLEAR_MAX (currently 100) times. A warning is
logged if this limit is reached.
- Adds a flag EC_FLAGS_CLEAR_ON_RESUME which is set to 1 if the DMI
system vendor is Samsung. This check could be replaced by several
more specific DMI vendor/product pairs, but it's likely that the bug
affects more Samsung products than just the five series mentioned
above. Further, it should not be harmful to run acpi_ec_clear() on
systems without the bug; it will return immediately after finding no
data waiting.
- Runs acpi_ec_clear() on initialisation (boot), from acpi_ec_add()
- Runs acpi_ec_clear() on wake, from acpi_ec_unblock_transactions()
References: https://bugzilla.kernel.org/show_bug.cgi?id=44161
References: https://bugzilla.kernel.org/show_bug.cgi?id=45461
References: https://bugzilla.kernel.org/show_bug.cgi?id=57271
References: https://bugzilla.kernel.org/attachment.cgi?id=126801
Suggested-by: Juan Manuel Cabo <juanmanuel.cabo@gmail.com>
Signed-off-by: Kieran Clancy <clancy.kieran@gmail.com>
Reviewed-by: Lan Tianyu <tianyu.lan@intel.com>
Reviewed-by: Dennis Jansen <dennis.jansen@web.de>
Tested-by: Kieran Clancy <clancy.kieran@gmail.com>
Tested-by: Juan Manuel Cabo <juanmanuel.cabo@gmail.com>
Tested-by: Dennis Jansen <dennis.jansen@web.de>
Tested-by: Maurizio D'Addona <mauritiusdadd@gmail.com>
Tested-by: San Zamoyski <san@plusnet.pl>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-01 00:42:28 +10:30
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2016-08-03 09:00:14 +08:00
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2006-09-26 19:50:33 +04:00
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2007-10-22 14:18:30 +04:00
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2016-08-03 16:01:24 +08:00
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2015-02-11 17:35:05 +01:00
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2015-06-11 13:21:38 +08:00
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2016-03-24 10:42:47 +08:00
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2016-09-07 16:50:21 +08:00
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2015-02-06 08:57:52 +08:00
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2017-08-11 14:36:28 +08:00
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2005-04-16 15:20:36 -07:00
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2006-09-26 19:50:33 +04:00
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2014-06-15 08:41:35 +08:00
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2010-10-21 18:24:57 +02:00
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2016-08-03 09:00:14 +08:00
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2015-05-15 14:16:48 +08:00
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ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.
It is reported that on several platforms, EC firmware will not respond
non-expected QR_EC (see EC_FLAGS_QUERY_HANDSHAKE, only write QR_EC when
SCI_EVT is set).
Unfortunately, ACPI specification doesn't define when the SCI_EVT should be
cleared by the firmware, thus the original implementation queued up second
QR_EC right after writing QR_EC command and before reading the returned
event value as at that time the SCI_EVT is ensured not cleared. This
behavior is also based on the assumption that the firmware should be able
to return 0x00 to indicate "no outstanding event". This behavior did fix
issues on Samsung platforms where the spurious query value of 0x00 is
supported and didn't break platforms in my test queue.
But recently, specific Acer, Asus, Lenovo platforms keep on blaming this
change.
This patch changes the behavior to re-check the SCI_EVT a bit later and
removes EC_FLAGS_QUERY_HANDSHAKE quirks, hoping this is the Windows
compliant EC driver behavior.
In order to be robust to the possible regressions, instead of removing the
quirk directly, this patch keeps the quirk code, removes the quirk users
and keeps old behavior for Samsung platforms.
Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
Link: https://bugzilla.kernel.org/show_bug.cgi?id=97381
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98111
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-and-tested-by: Tigran Gabrielyan <tigrangab@gmail.com>
Reported-and-tested-by: Adrien D <ghbdtn@openmailbox.org>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-06-11 13:21:45 +08:00
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2015-06-11 13:21:38 +08:00
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2012-09-28 15:22:00 +08:00
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2017-07-12 11:09:17 +08:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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ACPI / EC: Add parameter to force disable the GPE on suspend
After commit 8110dd281e15 (ACPI / sleep: EC-based wakeup from
suspend-to-idle on recent systems) the configuration of GPEs,
including the EC one, is not changed during suspend-to-idle on
recent systems. That's in order to make system wakeup events
generated by the EC work, in particular.
However, on some of the systems in question (for example on Dell
XPS13 9365), in addition to generating system wakeup events the
EC generates a heartbeat sequence of interrupts that have nothing
to do with wakeup while suspended, and the Low Power Idle S0 _DSM
interface doesn't change that behavior.
The users of those systems may prefer to disable the EC GPE during
system suspend, for the cost of non-functional power button wakeup
or similar, but currently there is no way to do that.
For this reason, add a new module parameter, ec_no_wakeup, for the
EC driver module that, if set, will cause the EC GPE to be disabled
during system suspend and re-enabled during the subsequent system
resume.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=192591#c106
Amends: 8110dd281e15 (ACPI / sleep: EC-based wakeup from suspend-to-idle on recent systems)
Reported-and-tested-by: Patrik Kullman <patrik.kullman@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-19 14:41:58 +02:00
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2007-05-29 16:43:02 +04:00
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2015-01-14 19:28:28 +08:00
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2007-05-29 16:43:02 +04:00
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2008-09-26 00:54:28 +04:00
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2008-09-25 21:00:31 +04:00
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2008-09-26 00:54:28 +04:00
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2008-11-12 01:40:19 +03:00
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2008-09-25 21:00:31 +04:00
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2014-06-15 08:41:35 +08:00
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2008-09-25 21:00:31 +04:00
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2015-08-12 11:12:02 +08:00
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2015-01-14 19:28:53 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-08-12 11:12:02 +08:00
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ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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2010-07-16 13:11:31 +02:00
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2016-09-07 16:50:08 +08:00
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2016-08-03 09:00:14 +08:00
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2006-09-26 19:50:33 +04:00
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2014-10-29 11:33:49 +08:00
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ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
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2017-06-15 09:41:47 +08:00
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2009-02-21 12:18:13 -05:00
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2015-02-27 14:48:15 +08:00
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2015-02-27 14:48:24 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:57:52 +08:00
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2016-08-03 16:01:24 +08:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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2016-08-03 16:01:24 +08:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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2016-08-03 16:01:24 +08:00
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2015-02-06 08:57:59 +08:00
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2005-04-16 15:20:36 -07:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2014-10-14 14:24:01 +08:00
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2005-04-16 15:20:36 -07:00
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2006-09-26 19:50:33 +04:00
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2005-04-16 15:20:36 -07:00
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2007-11-21 03:23:26 +03:00
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2014-10-14 14:24:01 +08:00
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2015-02-27 14:48:15 +08:00
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2007-11-21 03:23:26 +03:00
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2005-04-16 15:20:36 -07:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2007-11-21 03:23:26 +03:00
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2014-10-14 14:24:01 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2015-02-27 14:48:15 +08:00
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2008-09-25 21:00:31 +04:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2015-02-27 14:48:15 +08:00
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2006-09-26 19:50:33 +04:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2015-02-27 14:48:15 +08:00
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2006-09-26 19:50:33 +04:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2006-09-26 19:50:33 +04:00
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2017-06-14 13:59:18 +08:00
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2014-10-14 14:23:49 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-05-15 14:16:17 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-02-06 08:58:05 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-02-06 08:58:05 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-02-27 14:48:15 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-02-06 08:58:05 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
|
|
|
|
2015-02-06 08:58:05 +08:00
|
|
|
|
ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2015-02-06 08:57:59 +08:00
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2016-03-24 10:42:47 +08:00
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2015-02-06 08:57:59 +08:00
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2016-03-24 10:42:47 +08:00
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2015-02-06 08:57:59 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2015-02-27 14:48:15 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:58:05 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-11 17:35:05 +01:00
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2015-02-06 08:57:59 +08:00
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2015-02-11 17:35:05 +01:00
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2015-02-06 08:57:59 +08:00
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2015-02-11 17:35:05 +01:00
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ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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2017-08-11 14:36:28 +08:00
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ACPI: EC: Fix an EC event IRQ storming issue
The EC event IRQ (SCI_EVT) can only be handled by submitting QR_EC. As the
EC driver handles SCI_EVT in a workqueue, after SCI_EVT is flagged and
before QR_EC is submitted, there is a period risking IRQ storming. EC IRQ
must be masked for this period but linux EC driver never does so.
No end user notices the IRQ storming and no developer fixes this known
issue because:
1. The EC IRQ is always edge triggered GPE, and
2. The kernel can execute no-op EC IRQ handler very fast.
For edge-triggered EC GPE platforms, it is only reported of post-resume EC
event lost issues, there won't be an IRQ storming. For level triggered EC
GPE platforms, fortunately the kernel is always fast enough to execute such
a no-op EC IRQ handler so that the IRQ handler won't be accumulated to
starve the task contexts, causing a real IRQ storming.
But the IRQ storming actually can still happen when:
1. The EC IRQ performs like level triggered GPE, and
2. The kernel EC debugging log is turned on but the console is slow enough.
There are more and more platforms using EC GPE as wake GPE where the EC GPE
is likely designed as level triggered. Then when EC debugging log is
enabled, the EC IRQ handler is no longer a no-op but dumps IRQ status to
the consoles. If the consoles are slow enough, the EC IRQs can arrive much
faster than executing the handler. Finally the accumulated EC event IRQ
handlers starve the task contexts, causing the IRQ storming to occur, and
the kernel hangs can be observed during boot/resume.
This patch fixes this issue by masking EC IRQ for this period:
1. Begins when there is an SCI_EVT IRQ pending, and
2. Ends when there is a QR_EC completed (SCI_EVT acknowledged).
Tested-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: Feng Chenzhou <chenzhoux.feng@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-14 13:59:09 +08:00
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2015-06-11 13:21:32 +08:00
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ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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|
ACPI / EC: Add query flushing support
This patch implementes the QR_EC flushing support.
Grace periods are implemented from the detection of an SCI_EVT to the
submission/completion of the QR_EC transaction. During this period, all
EC command transactions are allowed to be submitted.
Note that query periods and event periods are intentionally distiguished to
allow further improvements.
1. Query period: from the detection of an SCI_EVT to the sumission of the
QR_EC command. This period is used for storming prevention, as currently
QR_EC is deferred to a work queue rather than directly issued from the
IRQ context even there is no other transactions pending, so malicous
SCI_EVT GPE can act like "level triggered" to trigger a GPE storm. We
need to be prepared for this. And in the future, we may change it to be
a part of the advance_transaction() where we will try QR_EC submission
in appropriate positions to avoid such GPE storming.
2. Event period: from the detection of an SCI_EVT to the completion of the
QR_EC command. We may extend it to the completion of _Qxx evaluation.
This is actually a grace period for event flushing, but we only flush
queries due to the reason stated in known issue 1. That's also why we
use EC_FLAGS_EVENT_xxx. During this period, QR_EC transactions need to
pass the flushable submission check.
In this patch, the following flags are implemented:
1. EC_FLAGS_EVENT_ENABLED: this is derived from the old
EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT handlings.
With this flag, the logics implemented by the original flag are
extended:
1. Old logic: unless both of the flags are set, the event poller will
not be scheduled, and
2. New logic: as soon as both of the flags are set, the evet poller will
be scheduled.
2. EC_FLAGS_EVENT_DETECTED: this is also derived from the old
EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT detection. It thus
can be used to indicate the storming prevention period for query
submission.
acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
implement this period so that acpi_set_gpe() can be invoked under the
"reference count > 0" condition.
3. EC_FLAGS_EVENT_PENDING: this is newly added to indicate the grace period
for event flushing (query flushing for now).
acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
implement this period so that the flushing process can wait until the
event handling (query transaction for now) to be completed.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Ortwin Glück <odi@odi.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-06 08:58:10 +08:00
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2015-02-11 17:35:05 +01:00
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ACPI / EC: Add query flushing support
This patch implementes the QR_EC flushing support.
Grace periods are implemented from the detection of an SCI_EVT to the
submission/completion of the QR_EC transaction. During this period, all
EC command transactions are allowed to be submitted.
Note that query periods and event periods are intentionally distiguished to
allow further improvements.
1. Query period: from the detection of an SCI_EVT to the sumission of the
QR_EC command. This period is used for storming prevention, as currently
QR_EC is deferred to a work queue rather than directly issued from the
IRQ context even there is no other transactions pending, so malicous
SCI_EVT GPE can act like "level triggered" to trigger a GPE storm. We
need to be prepared for this. And in the future, we may change it to be
a part of the advance_transaction() where we will try QR_EC submission
in appropriate positions to avoid such GPE storming.
2. Event period: from the detection of an SCI_EVT to the completion of the
QR_EC command. We may extend it to the completion of _Qxx evaluation.
This is actually a grace period for event flushing, but we only flush
queries due to the reason stated in known issue 1. That's also why we
use EC_FLAGS_EVENT_xxx. During this period, QR_EC transactions need to
pass the flushable submission check.
In this patch, the following flags are implemented:
1. EC_FLAGS_EVENT_ENABLED: this is derived from the old
EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT handlings.
With this flag, the logics implemented by the original flag are
extended:
1. Old logic: unless both of the flags are set, the event poller will
not be scheduled, and
2. New logic: as soon as both of the flags are set, the evet poller will
be scheduled.
2. EC_FLAGS_EVENT_DETECTED: this is also derived from the old
EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT detection. It thus
can be used to indicate the storming prevention period for query
submission.
acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
implement this period so that acpi_set_gpe() can be invoked under the
"reference count > 0" condition.
3. EC_FLAGS_EVENT_PENDING: this is newly added to indicate the grace period
for event flushing (query flushing for now).
acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
implement this period so that the flushing process can wait until the
event handling (query transaction for now) to be completed.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Ortwin Glück <odi@odi.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-06 08:58:10 +08:00
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ACPI: EC: Fix an EC event IRQ storming issue
The EC event IRQ (SCI_EVT) can only be handled by submitting QR_EC. As the
EC driver handles SCI_EVT in a workqueue, after SCI_EVT is flagged and
before QR_EC is submitted, there is a period risking IRQ storming. EC IRQ
must be masked for this period but linux EC driver never does so.
No end user notices the IRQ storming and no developer fixes this known
issue because:
1. The EC IRQ is always edge triggered GPE, and
2. The kernel can execute no-op EC IRQ handler very fast.
For edge-triggered EC GPE platforms, it is only reported of post-resume EC
event lost issues, there won't be an IRQ storming. For level triggered EC
GPE platforms, fortunately the kernel is always fast enough to execute such
a no-op EC IRQ handler so that the IRQ handler won't be accumulated to
starve the task contexts, causing a real IRQ storming.
But the IRQ storming actually can still happen when:
1. The EC IRQ performs like level triggered GPE, and
2. The kernel EC debugging log is turned on but the console is slow enough.
There are more and more platforms using EC GPE as wake GPE where the EC GPE
is likely designed as level triggered. Then when EC debugging log is
enabled, the EC IRQ handler is no longer a no-op but dumps IRQ status to
the consoles. If the consoles are slow enough, the EC IRQs can arrive much
faster than executing the handler. Finally the accumulated EC event IRQ
handlers starve the task contexts, causing the IRQ storming to occur, and
the kernel hangs can be observed during boot/resume.
This patch fixes this issue by masking EC IRQ for this period:
1. Begins when there is an SCI_EVT IRQ pending, and
2. Ends when there is a QR_EC completed (SCI_EVT acknowledged).
Tested-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: Feng Chenzhou <chenzhoux.feng@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-14 13:59:09 +08:00
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2015-06-11 13:21:32 +08:00
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2017-08-11 14:36:28 +08:00
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ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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2016-08-03 16:01:24 +08:00
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2017-09-26 16:54:03 +08:00
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2016-08-03 16:01:24 +08:00
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2016-10-05 10:33:16 -07:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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2017-07-20 03:43:12 +02:00
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2016-10-05 10:33:16 -07:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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2015-06-11 13:21:38 +08:00
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2015-09-24 14:54:54 +08:00
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2015-06-11 13:21:38 +08:00
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2015-09-24 14:54:54 +08:00
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2015-06-11 13:21:38 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2014-06-15 08:41:35 +08:00
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2006-09-26 19:50:33 +04:00
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2008-09-25 21:00:31 +04:00
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2014-10-14 14:24:01 +08:00
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2012-10-23 01:29:27 +02:00
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2014-06-15 08:42:07 +08:00
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2008-09-25 21:00:31 +04:00
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2012-10-23 01:29:27 +02:00
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2008-09-25 21:00:31 +04:00
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2006-09-26 19:50:33 +04:00
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2015-06-11 13:21:23 +08:00
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2015-06-11 13:21:38 +08:00
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2015-06-11 13:21:23 +08:00
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2015-06-11 13:21:38 +08:00
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2015-06-11 13:21:23 +08:00
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2015-01-14 19:28:22 +08:00
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2008-09-25 21:00:31 +04:00
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2013-11-15 11:41:29 -08:00
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2014-06-15 08:41:17 +08:00
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2014-06-15 08:42:07 +08:00
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2012-10-23 01:29:38 +02:00
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2015-02-27 14:48:15 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2014-06-15 08:41:17 +08:00
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2013-11-15 11:41:29 -08:00
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2015-06-11 13:21:38 +08:00
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2015-06-11 13:21:51 +08:00
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2015-06-11 13:21:38 +08:00
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2012-10-23 01:29:38 +02:00
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2014-06-15 08:41:35 +08:00
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2014-06-15 08:42:07 +08:00
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2015-06-11 13:21:23 +08:00
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2014-08-21 14:41:13 +08:00
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2015-06-11 13:21:32 +08:00
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2014-06-15 08:42:07 +08:00
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2014-06-15 08:41:35 +08:00
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2014-06-15 08:42:07 +08:00
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2015-06-11 13:21:23 +08:00
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2014-06-15 08:42:07 +08:00
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2015-01-14 19:28:22 +08:00
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2014-06-15 08:41:35 +08:00
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2014-10-29 11:33:49 +08:00
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2014-08-21 14:41:13 +08:00
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2015-06-11 13:21:23 +08:00
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2014-08-21 14:41:13 +08:00
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2015-06-11 13:21:23 +08:00
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2015-06-11 13:21:32 +08:00
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2014-08-21 14:41:13 +08:00
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2014-06-15 08:41:35 +08:00
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2015-06-11 13:21:23 +08:00
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2008-09-25 21:00:31 +04:00
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2008-11-08 21:42:30 +03:00
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2015-01-14 19:28:22 +08:00
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2014-06-15 08:41:35 +08:00
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2008-11-08 21:42:30 +03:00
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2012-10-23 01:30:12 +02:00
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2014-06-15 08:41:35 +08:00
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2015-02-06 08:58:05 +08:00
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2017-08-11 14:36:28 +08:00
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2015-02-06 08:58:05 +08:00
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2014-06-15 08:41:35 +08:00
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2015-01-14 19:28:22 +08:00
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ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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2015-02-11 17:35:05 +01:00
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2015-01-14 19:28:22 +08:00
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2014-06-15 08:41:35 +08:00
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2012-10-23 01:30:12 +02:00
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2014-06-15 08:41:35 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2017-01-20 16:42:48 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2015-09-24 14:54:54 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2017-01-20 16:42:48 +08:00
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|
|
ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2015-09-24 14:54:54 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2015-06-11 13:21:38 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2008-09-25 21:00:31 +04:00
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2008-03-21 17:07:03 +03:00
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2009-08-30 03:06:14 +04:00
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2013-05-06 03:23:40 +00:00
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2014-10-14 14:24:01 +08:00
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2009-08-30 03:06:14 +04:00
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2010-10-21 18:24:57 +02:00
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2009-08-30 03:06:14 +04:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2014-06-15 08:41:35 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2014-06-15 08:41:35 +08:00
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2009-08-30 03:06:14 +04:00
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2013-09-12 03:32:04 -04:00
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2012-10-23 01:29:27 +02:00
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2009-08-30 03:06:14 +04:00
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2012-10-23 01:29:27 +02:00
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2006-12-07 18:42:16 +03:00
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2008-03-21 17:07:15 +03:00
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2005-03-19 01:10:05 -05:00
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2008-09-26 00:54:28 +04:00
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2009-08-30 03:06:14 +04:00
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2006-09-05 12:12:24 -04:00
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2008-09-25 21:00:31 +04:00
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2014-10-14 14:24:01 +08:00
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2008-09-25 21:00:31 +04:00
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2012-10-23 01:29:27 +02:00
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2015-02-06 08:57:59 +08:00
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2015-02-11 17:35:05 +01:00
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2015-02-06 08:57:52 +08:00
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2015-02-27 14:48:24 +08:00
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2008-09-25 21:00:31 +04:00
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2008-09-26 00:54:28 +04:00
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2015-02-27 14:48:15 +08:00
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2008-11-12 01:40:19 +03:00
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2014-10-29 11:33:43 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
|
|
|
|
2014-10-29 11:33:43 +08:00
|
|
|
|
ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
|
|
|
|
2014-10-29 11:33:43 +08:00
|
|
|
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2015-02-06 08:58:05 +08:00
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2017-08-11 14:36:28 +08:00
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|
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2015-02-27 14:48:15 +08:00
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2008-09-26 00:54:28 +04:00
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2015-02-06 08:57:59 +08:00
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2015-02-27 14:48:24 +08:00
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2015-02-06 08:57:52 +08:00
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2012-10-23 01:29:27 +02:00
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2008-09-25 21:00:31 +04:00
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2006-09-05 12:12:24 -04:00
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2009-08-30 03:06:14 +04:00
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2005-07-23 04:08:00 -04:00
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2006-09-05 12:12:24 -04:00
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2005-08-11 17:32:05 -04:00
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2014-10-14 14:24:01 +08:00
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2008-09-26 00:54:28 +04:00
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2006-06-27 00:41:40 -04:00
|
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2008-09-26 00:54:28 +04:00
|
|
|
|
|
|
|
|
|
ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
|
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2012-10-23 01:29:27 +02:00
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2006-09-26 19:50:33 +04:00
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2005-04-16 15:20:36 -07:00
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2007-02-15 23:16:18 +03:00
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2008-09-25 21:00:31 +04:00
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2007-02-15 23:16:18 +03:00
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2005-04-16 15:20:36 -07:00
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2009-12-24 11:34:16 +03:00
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2009-08-30 03:06:14 +04:00
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2009-12-24 11:34:16 +03:00
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2006-09-26 19:50:33 +04:00
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2005-04-16 15:20:36 -07:00
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2008-09-25 21:00:31 +04:00
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2012-10-23 01:29:27 +02:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2008-12-09 20:45:30 +01:00
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2007-03-07 22:28:00 +03:00
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2008-09-26 00:54:28 +04:00
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2009-08-30 03:06:14 +04:00
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2007-03-07 22:28:00 +03:00
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2008-12-09 20:45:30 +01:00
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2007-03-07 22:28:00 +03:00
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2008-09-26 00:54:28 +04:00
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2008-09-25 21:00:31 +04:00
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2009-08-30 03:06:14 +04:00
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2007-03-07 22:28:00 +03:00
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2014-10-14 14:24:01 +08:00
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2006-09-26 19:50:33 +04:00
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2008-09-26 00:54:28 +04:00
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2006-09-26 19:50:33 +04:00
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2009-08-30 03:06:14 +04:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2006-09-26 19:50:33 +04:00
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2006-12-07 18:42:17 +03:00
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2008-09-26 00:54:28 +04:00
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2009-08-30 03:06:14 +04:00
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2006-09-26 19:50:33 +04:00
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2012-10-23 01:29:38 +02:00
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2005-04-16 15:20:36 -07:00
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2006-09-26 19:50:33 +04:00
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2005-04-16 15:20:36 -07:00
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2007-03-07 22:28:00 +03:00
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2005-04-16 15:20:36 -07:00
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2014-10-14 14:24:01 +08:00
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2005-04-16 15:20:36 -07:00
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2005-08-11 17:32:05 -04:00
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2005-04-16 15:20:36 -07:00
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2007-03-07 22:28:00 +03:00
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2005-04-16 15:20:36 -07:00
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2006-10-27 01:47:34 -04:00
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2014-10-14 14:24:01 +08:00
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2005-07-23 04:08:00 -04:00
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2008-09-26 00:54:28 +04:00
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2014-10-14 14:24:01 +08:00
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2006-09-05 12:12:24 -04:00
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2009-08-30 03:06:14 +04:00
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2005-07-23 04:08:00 -04:00
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2006-10-03 22:49:00 -04:00
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2012-01-18 13:44:08 -06:00
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2015-02-06 08:57:52 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-27 14:48:24 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-27 14:48:24 +08:00
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ACPI / EC: Add PM operations to improve event handling for resume process
This patch makes 2 changes:
1. Restore old behavior
Originally, EC driver stops handling both events and transactions in
acpi_ec_block_transactions(), and restarts to handle transactions in
acpi_ec_unblock_transactions_early(), restarts to handle both events and
transactions in acpi_ec_unblock_transactions().
While currently, EC driver still stops handling both events and
transactions in acpi_ec_block_transactions(), but restarts to handle both
events and transactions in acpi_ec_unblock_transactions_early().
This patch tries to restore the old behavior by dropping
__acpi_ec_enable_event() from acpi_unblock_transactions_early().
2. Improve old behavior
However this still cannot fix the real issue as both of the
acpi_ec_unblock_xxx() functions are invoked in the noirq stage. Since the
EC driver actually doesn't implement the event handling in the polling
mode, re-enabling the event handling too early in the noirq stage could
result in the problem that if there is no triggering source causing
advance_transaction() to be invoked, pending SCI_EVT cannot be detected by
the EC driver and _Qxx cannot be triggered.
It actually makes sense to restart the event handling in any point during
resuming after the noirq stage. Just like the boot stage where the event
handling is enabled in .add(), this patch further moves
acpi_ec_enable_event() to .resume(). After doing that, the following 2
functions can be combined:
acpi_ec_unblock_transactions_early()/acpi_ec_unblock_transactions().
The differences of the event handling availability between the old behavior
(this patch isn't applied) and the new behavior (this patch is applied) are
as follows:
!Applied Applied
before suspend Y Y
suspend before EC Y Y
suspend after EC Y Y
suspend_late Y Y
suspend_noirq Y (actually N) Y (actually N)
resume_noirq Y (actually N) Y (actually N)
resume_late Y (actually N) Y (actually N)
resume before EC Y (actually N) Y (actually N)
resume after EC Y (actually N) Y
after resume Y (actually N) Y
Where "actually N" means if there is no triggering source, the EC driver
is actually not able to notice the pending SCI_EVT occurred in the noirq
stage. So we can clearly see that this patch has improved the situation.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:36 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:57:52 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-06 08:57:52 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:57:52 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-27 14:48:24 +08:00
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2015-02-06 08:57:59 +08:00
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2015-02-27 14:48:24 +08:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
|
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2016-08-03 16:01:24 +08:00
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2015-02-06 08:57:52 +08:00
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2015-02-27 14:48:15 +08:00
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2015-02-06 08:57:52 +08:00
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2017-01-20 16:42:48 +08:00
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2010-04-09 01:40:38 +02:00
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2010-03-04 01:52:58 +01:00
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2012-10-23 01:29:27 +02:00
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2010-03-04 01:52:58 +01:00
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2015-02-06 08:57:52 +08:00
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2012-10-23 01:29:27 +02:00
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2010-03-04 01:52:58 +01:00
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2010-04-09 01:40:38 +02:00
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2010-04-09 01:39:40 +02:00
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2015-02-06 08:57:52 +08:00
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2010-04-09 01:39:40 +02:00
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2005-04-16 15:20:36 -07:00
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2015-01-14 19:28:28 +08:00
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2015-09-24 14:54:48 +08:00
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2015-01-14 19:28:28 +08:00
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2007-05-29 16:43:02 +04:00
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2014-10-14 14:24:01 +08:00
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2007-05-29 16:43:02 +04:00
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2012-10-23 01:29:27 +02:00
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2015-01-14 19:28:28 +08:00
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2007-09-26 19:43:22 +04:00
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2012-10-23 01:29:27 +02:00
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2007-05-29 16:43:02 +04:00
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2015-09-24 14:54:48 +08:00
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2007-05-29 16:43:02 +04:00
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2007-10-24 18:26:00 +02:00
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2015-01-14 19:28:28 +08:00
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2014-10-14 14:24:01 +08:00
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2012-10-23 01:29:27 +02:00
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2007-10-24 18:26:00 +02:00
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2015-09-24 14:54:48 +08:00
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2015-01-14 19:28:28 +08:00
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2007-05-29 16:43:02 +04:00
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2012-10-23 01:29:27 +02:00
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2015-04-22 00:25:36 +01:00
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2015-01-14 19:28:28 +08:00
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2007-05-29 16:43:02 +04:00
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2015-09-24 14:54:48 +08:00
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2007-05-29 16:43:02 +04:00
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2005-04-16 15:20:36 -07:00
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2015-08-12 11:12:02 +08:00
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2005-07-23 04:08:00 -04:00
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2015-08-12 11:12:02 +08:00
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2014-10-14 14:24:01 +08:00
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2015-02-27 14:48:15 +08:00
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2009-12-24 11:34:16 +03:00
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2015-02-27 14:48:15 +08:00
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2015-08-12 11:12:02 +08:00
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2009-12-24 11:34:16 +03:00
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2015-01-14 19:28:53 +08:00
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2009-12-24 11:34:16 +03:00
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2015-01-14 19:28:33 +08:00
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2015-08-12 11:12:02 +08:00
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2014-04-30 00:21:20 +09:30
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2015-01-14 19:28:53 +08:00
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2015-08-12 11:12:02 +08:00
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2015-01-14 19:28:53 +08:00
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2015-08-12 11:12:02 +08:00
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2014-04-30 00:21:20 +09:30
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2015-09-24 14:54:48 +08:00
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2016-08-03 09:00:14 +08:00
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2015-09-24 14:54:48 +08:00
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2007-05-29 16:43:02 +04:00
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2015-08-12 11:12:02 +08:00
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2015-11-15 22:42:27 +01:00
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2015-08-12 11:12:02 +08:00
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2015-01-14 19:28:33 +08:00
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2009-12-24 11:34:16 +03:00
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2015-06-11 13:21:38 +08:00
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2015-06-11 13:21:32 +08:00
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2009-12-24 11:34:16 +03:00
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2015-06-11 13:21:32 +08:00
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|
ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't
implement the draining support, it only cleans up code so that further
draining support is possible.
The draining behavior is expected by some platforms (for example, Samsung)
where SCI_EVT is set only once for a set of events and might be cleared for
the very first QR_EC command issued after SCI_EVT is set. EC firmware on
such platforms will return 0x00 to indicate "no outstanding event". Thus
after seeing an SCI_EVT indication, EC driver need to fetch events until
0x00 returned (see acpi_ec_clear()).
Issue 1 - acpi_ec_submit_query():
It's reported on Samsung laptops that SCI_EVT isn't checked when the
transactions are advanced in ec_poll(), which leads to SCI_EVT triggering
source lost:
If no EC GPE IRQs are arrived after that, EC driver cannot detect this
event and handle it.
See comment 244/247 for kernel bugzilla 44161.
This patch fixes this issue by moving SCI_EVT checks into
advance_transaction(). So that SCI_EVT is checked each time we are going to
handle the EC firmware indications. And this check will happen for both IRQ
context and task context.
Since after doing that, SCI_EVT is also checked after completing a
transaction, ec_check_sci() and ec_check_sci_sync() can be removed.
Issue 2 - acpi_ec_complete_query():
We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining
QR_EC after writing a QR_EC command and before reading the event. After
reading the event, SCI_EVT might be cleared by the firmware, thus it may
not be possible to queue such a draining QR_EC at that time.
But putting the EC_FLAGS_QUERY_PENDING clearing code after
start_transaction() is wrong as there are chances that after
start_transaction(), QR_EC can fail to be sent. If this happens,
EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the
draining QR_EC will also be queued earlier than expected.
This patch also moves this code into advance_transaction() where QR_EC is
just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue.
Notes:
1. After introducing the 2 SCI_EVT related handlings into
advance_transaction(), a next QR_EC can be queued right after writing
the current QR_EC command and before reading the event. But this still
hasn't implemented the draining behavior as the draining support
requires:
If a previous returned event value isn't 0x00, a draining QR_EC need
to be issued even when SCI_EVT isn't set.
2. In this patch, acpi_os_execute() is also converted into a seperate work
item to avoid invoking kmalloc() in the atomic context. We can do this
because of the previous global lock fix.
3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up
multiple work items (created by acpi_os_execute()), this can be covered
by only using a single work item. But this patch still keeps this flag
as there are different usages in the driver initialization steps relying
on this flag.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-by: Kieran Clancy <clancy.kieran@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-01-14 19:28:47 +08:00
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2014-10-14 14:24:01 +08:00
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2015-06-11 13:21:32 +08:00
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2015-06-11 13:21:51 +08:00
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2015-06-11 13:21:32 +08:00
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2015-06-11 13:21:38 +08:00
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2005-07-23 04:08:00 -04:00
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2005-04-16 15:20:36 -07:00
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2010-12-13 13:38:46 +08:00
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2005-07-23 04:08:00 -04:00
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2014-06-15 08:41:35 +08:00
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2007-03-07 22:28:00 +03:00
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2007-05-04 14:16:19 +02:00
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2014-06-15 08:41:35 +08:00
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2015-01-14 19:28:22 +08:00
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2014-06-15 08:42:07 +08:00
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ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
This patch switches EC driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode where
the GPE lock is not held for acpi_ec_gpe_handler() and the ACPICA internal
GPE enabling/disabling/clearing operations are bypassed so that further
improvements are possible with the GPE APIs.
There are 2 strong reasons for deploying raw GPE handler mode in the EC
driver:
1. Some hardware logics can control their interrupts via their own
registers, so their interrupts can be disabled/enabled/acknowledged
without using the super IRQ controller provided functions. While there
is no mean (EC commands) for the EC driver to achieve this.
2. During suspending, the EC driver is still working for a while to
complete the platform firmware provided functionailities using ec_poll()
after all GPEs are disabled (see acpi_ec_block_transactions()), which
means the EC driver will drive the EC GPE out of the GPE core's control.
Without deploying the raw GPE handler mode, we can see many races between
the EC driver and the GPE core due to the above restrictions:
1. There is a race condition due to ACPICA internal GPE
disabling/clearing/enabling logics in acpi_ev_gpe_dispatch():
Orignally EC GPE is disabled (EN=0), cleared (STS=0) before invoking a
GPE handler and re-enabled (EN=1) after invoking a GPE handler in
acpi_ev_gpe_dispatch(). When re-enabling appears, GPE may be flagged
(STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() ec_poll()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1
This race condition is the root cause of different issues on different
silicon variations.
A. Silicon variation A:
On some platforms, GPE will be triggered due to "writing 1 to EN when
STS=1". This is because both EN and STS lines are wired to the GPE
trigger line.
1. Issue 1:
We can see no-op acpi_ec_gpe_handler() invoked on such platforms.
This is because:
a. event pending B: An event can arrive after ACPICA's GPE
clearing performed in acpi_ev_gpe_dispatch(), this event may
fail to be detected by EC_SC read that is performed before its
arrival;
b. event handling B: The event can be handled in ec_poll() because
EC lock is released after acpi_ec_gpe_handler() invocation;
c. There is no code in ec_poll() to clear STS but the GPE can
still be triggered by the EN=1 write performed in
acpi_ev_finish_gpe(), this leads to a no-op EC GPE handler
invocation;
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 1:
If we removed GPE disabling/enabling code from
acpi_ev_gpe_dispatch(), we could still see no-op GPE handlers
triggered by the event arriving after the GPE clearing and before
the GPE handling on both silicon variation A and B. This can only
occur if the CPU is very slow (timing slice between STS=0 write
and EC_SC read should be short enough before hardware sets another
GPE indication). Thus this is very rare and is not what we need to
fix.
B. Silicon variation B:
On other platforms, GPE may not be triggered due to "writing 1 to EN
when STS=1". This is because only STS line is wired to the GPE
trigger line.
2. Issue 2:
We can see GPE loss on such platforms. This is because:
a. event pending B vs. event handling A: An event can arrive after
ACPICA's GPE handling performed in acpi_ev_gpe_dispatch(), or
event pending C vs. event handling B: An event can arrive after
Linux's GPE handling performed in ec_poll(),
these events may fail to be detected by EC_SC read that is
performed before their arrival;
b. The GPE cannot be triggered by EN=1 write performed in
acpi_ev_finish_gpe();
c. If no polling mechanism is implemented in the driver for the
pending event (for example, SCI_EVT), this event is lost due to
no GPE being triggered.
Note 2:
On most platforms, there might be another rule that GPE may not be
triggered due to "writing 1 to STS when STS=1 and EN=1".
Then on silicon variation B, an even worse case is if the issue 2
event loss happens, further events may never trigger GPE again on
such platforms due to being blocked by the current STS=1. Unless
someone clears STS, all events have to be polled.
2. There is a race condition due to lacking in GPE status checking in EC
driver:
Originally, GPE status is checked in ACPICA core but not checked in
the GPE handler. Thus since the status checking and handling is not
locked, it can be interrupted by another handling path.
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_detect() ec_poll()
if (EN==1 && STS==1)
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
acpi_ev_gpe_dispatch()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
EC_SC read
Unlock(EC)
*****************************************************************
3. Issue 3:
We can see no-op acpi_ec_gpe_handler() invoked on both silicon
variation A and B. This is because:
a. event pending A: An event can arrive to trigger an EC GPE and
ACPICA checks it and is about to invoke the EC GPE handler;
b. event handling A: The event can be handled in ec_poll() because
EC lock is not held after the GPE status checking;
c. event handling B: Then when the EC GPE handler is invoked, it
becomes a no-op GPE handler invocation.
d. As no-op GPE handler invocations are counted by the EC driver
to trigger the command storming conditions, the wrong no-op
GPE handler invocations thus can easily trigger wrong command
storming conditions.
Note 3:
This no-op GPE handler invocation is rare because the time between
the IRQ arrival and the acpi_ec_gpe_handler() invocation is less than
the timeout value waited in ec_poll(). So most of the no-op GPE
handler invocations are caused by the reason described in issue 1.
3. There is a race condition due to ACPICA internal GPE clearing logic in
acpi_enable_gpe():
During runtime, acpi_enable_gpe() can be invoked by the EC storming
prevention code. When it is invoked, GPE may be flagged (STS=1).
=================================================================
(event pending A)
=================================================================
acpi_ev_gpe_dispatch() acpi_ec_transaction()
EN=0
STS=0
acpi_ec_gpe_handler()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
EC_SC read
EC_SC handled
Unlock(EC)
*****************************************************************
EN=1 ?
Lock(EC)
Unlock(EC)
=================================================================
(event pending B)
=================================================================
acpi_enable_gpe()
STS=0
EN=1
4. Issue 4:
We can see GPE loss on both silicon variation A and B platforms.
This is because:
a. event pending B: An event can arrive right before ACPICA's GPE
clearing performed in acpi_enable_gpe();
b. If the GPE is cleared when GPE is disabled, then EN=1 write in
acpi_enable_gpe() cannot trigger this GPE;
c. If no polling mechanism is implemented in the driver for this
event (for example, SCI_EVT), this event is lost due to no GPE
being triggered.
Note 4:
Currently we don't have this issue, but after we switch the EC
driver into ACPI_GPE_DISPATCH_RAW_HANDLER mode, we need to take care
of handling this because the EN=1 write in acpi_ev_gpe_dispatch()
will be abandoned.
There might be more race issues for the current GPE handler usages. This is
because the EC IRQ's enabling/disabling/checking/clearing/handling
operations should be locked by a single lock that is under the EC driver's
control to achieve the serialization. Which means we need to invoke GPE
APIs with EC driver's lock held and all ACPICA internal GPE operations
related to the GPE handler should be abandoned. Invoking GPE APIs inside of
the EC driver lock and bypassing ACPICA internal GPE operations requires
the ACPI_GPE_DISPATCH_RAW_HANDLER mode where the same lock used by the APIs
are released prior than invoking the handlers. Otherwise, we can see dead
locks due to circular locking dependencies (see Reference below).
This patch then switches the EC driver into the
ACPI_GPE_DISPATCH_RAW_HANDLER mode so that it can perform correct GPE
operations using the GPE APIs:
1. Bypasses EN modifications performed in acpi_ev_gpe_dispatch() by
using acpi_install_gpe_raw_handler() and invoking all GPE APIs with EC
spin lock held. This can fix issue 1 as it makes a non frequent GPE
enabling/disabling environment.
2. Bypasses STS clearing performed in acpi_enable_gpe() by replacing
acpi_enable_gpe()/acpi_disable_gpe() with acpi_set_gpe(). This can fix
issue 4. And this can also help to fix issue 1 as it makes a no sudden
GPE clearing environment when GPE is frequently enabled/disabled.
3. Ensures STS acknowledged before handling by invoking acpi_clear_gpe()
in advance_transaction(). This can finally fix issue 1 even in a
frequent GPE enabling/disabling environment. And this can also finally
fix issue 3 when issue 2 is fixed.
Note 3:
GPE clearing is edge triggered W1C, which means we can clear it right
before handling it. Since all EC GPE indications are handled in
advance_transaction() by previous commits, we can now move GPE clearing
into it to implement the correct GPE clearing.
Note 4:
We can use acpi_set_gpe() which is not shared GPE safer instead of
acpi_enable_gpe()/acpi_disable_gpe() because EC GPE is not shared by
other hardware, which is mentioned in the ACPI specification 5.0, 12.6
Interrupt Model: "OSPM driver treats this as an edge event (the EC SCI
cannot be shared)". So we can stop using shared GPE safer APIs
acpi_enable_gpe()/acpi_disable_gpe() in the EC driver. Otherwise
cleanups need to be made in acpi_ev_enable_gpe() to bypass the GPE
clearing logic before keeping acpi_enable_gpe().
This patch also invokes advance_transaction() when GPE is re-enabled in the
task context which:
1. Ensures EN=1 can trigger GPE by checking and handling EC status register
right after EN=1 writes. This can fix issue 2.
After applying this patch, without frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() ec_poll()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 1 (event pending B) can arrive as a next GPE
due to the previous IRQ context STS=0 write. And if it is handled by
ec_poll() (event handling B), as it is also acknowledged by ec_poll(), the
event pending for issue 2 (event pending C) can properly arrive as a next
GPE after the task context STS=0 write. So no GPE will be lost and never
triggered due to GPE clearing performed in the wrong position. And since
all GPE handling is performed after a locked GPE status checking, we can
hardly see no-op GPE handler invocations due to issue 1 and 3. We may still
see no-op GPE handler invocations due to "Note 1", but as it is inevitable,
it needn't be fixed.
After applying this patch, with frequent GPE enablings considered:
=================================================================
(event pending A)
=================================================================
acpi_ec_gpe_handler() acpi_ec_transaction()
*****************************************************************
(event handling A)
Lock(EC)
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending B)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
*****************************************************************
(event handling B)
Lock(EC)
EN=1
if STS==1
advance_transaction()
if STS==1
STS=0
EC_SC read
=================================================================
(event pending C)
=================================================================
EC_SC handled
Unlock(EC)
*****************************************************************
The event pending for issue 2 can be manually handled by
advance_transaction(). And after the STS=0 write performed in the manual
triggered advance_transaction(), GPE can always arrive. So no GPE will be
lost due to frequent GPE disabling/enabling performed in the driver like
issue 4.
Note 5:
It's ideally when EN=1 write occurred, an IRQ thread should be woken up to
handle the GPE when the GPE was raised. But this requires the IRQ thread to
contain the poller code for all EC GPE indications, while currently some of
the indications are handled in the user tasks. It then is very hard for the
code to determine whether a user task should be invoked or the poller work
item should be scheduled. So we have to invoke advance_transaction()
directly now and it leaves us such a restriction for the GPE re-enabling:
it must be performed in the task context to avoid starving the GPEs.
As a conclusion: we can see the EC GPE is always handled in serial after
deploying the raw GPE handler mode:
Lock(EC)
if (STS==1)
STS=0
EC_SC read
EC_SC handled
Unlock(EC)
The EC driver specific lock is responsible to make the EC GPE handling
processes serialized so that EC can handle its GPE from both IRQ and task
contexts and the next IRQ can be ensured to arrive after this process.
Note 6:
We have many EC_FLAGS_MSI qurik users in the current driver. They all seem
to be suffering from unexpected GPE triggering source lost. And they are
false root caused to a timing issue. Since EC communication protocol has
already flow control defined, timing shouldn't be the root cause, while
this fix might be fixing the root cause of the old bugs.
Link: https://lkml.org/lkml/2014/11/4/974
Link: https://lkml.org/lkml/2014/11/18/316
Link: https://www.spinics.net/lists/linux-acpi/msg54340.html
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-05 16:27:22 +08:00
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2008-03-21 17:07:03 +03:00
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2005-04-16 15:20:36 -07:00
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2014-10-14 14:24:01 +08:00
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2005-04-16 15:20:36 -07:00
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2007-05-29 16:42:52 +04:00
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2010-03-17 13:14:13 -04:00
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2005-08-11 17:32:05 -04:00
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2005-04-16 15:20:36 -07:00
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2007-03-07 22:28:00 +03:00
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2010-03-17 13:14:13 -04:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2007-05-29 16:42:52 +04:00
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2006-06-27 00:41:40 -04:00
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2007-05-29 16:42:52 +04:00
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2017-01-20 16:42:48 +08:00
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2009-08-28 23:29:44 +04:00
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2008-01-11 02:42:57 +03:00
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2010-03-17 13:14:13 -04:00
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2008-01-11 02:42:51 +03:00
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2017-01-20 16:42:48 +08:00
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2009-08-28 23:29:44 +04:00
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2008-01-11 02:42:57 +03:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 00:41:40 -04:00
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2005-04-16 15:20:36 -07:00
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2014-10-14 14:24:01 +08:00
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2007-03-07 22:28:00 +03:00
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2016-09-07 16:50:08 +08:00
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2007-03-07 22:28:00 +03:00
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2014-10-14 14:24:01 +08:00
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2007-03-07 22:28:00 +03:00
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2012-10-23 01:29:27 +02:00
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2007-03-07 22:28:00 +03:00
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2007-05-29 16:43:02 +04:00
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2012-10-23 01:29:27 +02:00
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2015-06-11 13:21:32 +08:00
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ACPI / EC: Fix and clean up register access guarding logics.
In the polling mode, EC driver shouldn't access the EC registers too
frequently. Though this statement is concluded from the non-root caused
bugs (see links below), we've maintained the register access guarding
logics in the current EC driver. The guarding logics can be found here and
there, makes it hard to root cause real timing issues. This patch collects
the guarding logics into one single function so that all hidden logics
related to this can be seen clearly.
The current guarding related code also has several issues:
1. Per-transaction timestamp prevents inter-transaction guarding from being
implemented in the same place. We have an inter-transaction udelay() in
acpi_ec_transaction_unblocked(), this logic can be merged into ec_poll()
if we can use per-device timestamp. This patch completes such merge to
form a new ec_guard() function and collects all guarding related hidden
logics in it.
One hidden logic is: there is no inter-transaction guarding performed
for non MSI quirk (wait polling mode), this patch skips
inter-transaction guarding before wait_event_timeout() for the wait
polling mode to reveal the hidden logic.
The other hidden logic is: there is msleep() inter-transaction guarding
performed when the GPE storming is observed. As after merging this
commit:
Commit: e1d4d90fc0313d3d58cbd7912c90f8ef24df45ff
Subject: ACPI / EC: Refine command storm prevention support
EC_FLAGS_COMMAND_STORM is ensured to be cleared after invoking
acpi_ec_transaction_unlocked(), the msleep() guard logic will never
happen now. Since no one complains such change, this logic is likely
added during the old times where the EC race issues are not fixed and
the bugs are false root-caused to the timing issue. This patch simply
removes the out-dated logic. We can restore it by stop skipping
inter-transaction guarding for wait polling mode.
Two different delay values are defined for msleep() and udelay() while
they are merged in this patch to 550us.
2. time_after() causes additional delay in the polling mode (can only be
observed in noirq suspend/resume processes where polling mode is always
used) before advance_transaction() is invoked ("wait polling" log is
added before wait_event_timeout()). We can see 2 wait_event_timeout()
invocations. This is because time_after() ensures a ">" validation while
we only need a ">=" validation here:
[ 86.739909] ACPI: Waking up from system sleep state S3
[ 86.742857] ACPI : EC: 2: Increase command
[ 86.742859] ACPI : EC: ***** Command(RD_EC) started *****
[ 86.742861] ACPI : EC: ===== TASK (0) =====
[ 86.742871] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.742873] ACPI : EC: EC_SC(W) = 0x80
[ 86.742876] ACPI : EC: ***** Event started *****
[ 86.742880] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.743972] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.747966] ACPI : EC: ===== TASK (0) =====
[ 86.747977] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 86.747978] ACPI : EC: EC_DATA(W) = 0x06
[ 86.747981] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.751971] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755969] ACPI : EC: ===== TASK (0) =====
[ 86.755991] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 86.755993] ACPI : EC: EC_DATA(R) = 0x03
[ 86.755994] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 86.755995] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 86.755996] ACPI : EC: 1: Decrease command
This patch corrects this by using time_before() instead in ec_guard():
[ 54.283146] ACPI: Waking up from system sleep state S3
[ 54.285414] ACPI : EC: 2: Increase command
[ 54.285415] ACPI : EC: ***** Command(RD_EC) started *****
[ 54.285416] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.285417] ACPI : EC: ===== TASK (0) =====
[ 54.285424] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.285425] ACPI : EC: EC_SC(W) = 0x80
[ 54.285427] ACPI : EC: ***** Event started *****
[ 54.285429] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.287209] ACPI : EC: ===== TASK (0) =====
[ 54.287218] ACPI : EC: EC_SC(R) = 0x20 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=0
[ 54.287219] ACPI : EC: EC_DATA(W) = 0x06
[ 54.287222] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291190] ACPI : EC: ===== TASK (0) =====
[ 54.291210] ACPI : EC: EC_SC(R) = 0x21 SCI_EVT=1 BURST=0 CMD=0 IBF=0 OBF=1
[ 54.291213] ACPI : EC: EC_DATA(R) = 0x03
[ 54.291214] ACPI : EC: ~~~~~ wait polling ~~~~~
[ 54.291215] ACPI : EC: ***** Command(RD_EC) stopped *****
[ 54.291216] ACPI : EC: 1: Decrease command
After cleaning up all guarding logics, we have one single function
ec_guard() collecting all old, non-root-caused, hidden logics. Then we can
easily tune the logics in one place to respond to the bug reports.
Except the time_before() change, all other changes do not change the
behavior of the EC driver.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=12011
Link: https://bugzilla.kernel.org/show_bug.cgi?id=20242
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-05-15 14:16:42 +08:00
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2007-03-07 22:28:00 +03:00
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2007-05-29 16:43:02 +04:00
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2007-08-14 01:03:42 -04:00
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2008-12-16 16:46:12 +08:00
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2007-08-14 01:03:42 -04:00
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2008-12-16 16:46:12 +08:00
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2014-10-14 14:24:01 +08:00
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2007-08-14 01:03:42 -04:00
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2007-08-03 17:52:48 -04:00
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2007-05-29 16:43:02 +04:00
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2007-08-03 17:52:48 -04:00
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2008-11-03 14:26:40 -05:00
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2007-08-03 17:52:48 -04:00
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2009-04-01 01:33:15 -04:00
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2007-08-03 17:52:48 -04:00
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2017-06-15 09:41:35 +08:00
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2007-05-29 16:43:02 +04:00
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2017-06-15 09:41:47 +08:00
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2007-05-29 16:43:02 +04:00
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2008-11-03 14:26:40 -05:00
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2008-10-10 02:22:59 -04:00
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2007-05-29 16:43:02 +04:00
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2007-08-03 17:52:48 -04:00
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2007-05-29 16:43:02 +04:00
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2016-09-07 16:50:08 +08:00
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2016-09-07 16:50:21 +08:00
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2007-03-07 22:28:00 +03:00
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2007-03-07 22:28:00 +03:00
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2014-10-14 14:24:01 +08:00
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2015-02-06 08:57:52 +08:00
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2016-03-24 10:42:47 +08:00
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2017-01-20 16:42:48 +08:00
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2008-10-17 02:02:44 -04:00
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2007-03-07 22:28:00 +03:00
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2017-09-26 16:54:03 +08:00
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2007-03-07 22:28:00 +03:00
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2007-09-05 19:56:38 -04:00
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2005-04-16 15:20:36 -07:00
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2016-03-24 10:42:47 +08:00
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2016-07-08 09:25:05 +08:00
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2016-09-07 16:50:21 +08:00
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2016-09-07 16:50:21 +08:00
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2009-04-01 01:33:15 -04:00
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2016-09-07 16:50:08 +08:00
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2016-06-21 17:42:05 +08:00
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2016-09-07 16:50:27 +08:00
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2010-07-29 22:08:44 +02:00
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2012-02-06 08:17:08 -08:00
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2013-01-24 00:24:48 +01:00
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2006-06-27 00:41:40 -04:00
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2010-07-29 22:08:44 +02:00
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2006-09-26 19:50:33 +04:00
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2010-07-29 22:08:44 +02:00
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2006-09-26 19:50:33 +04:00
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2016-06-03 10:26:12 +08:00
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ACPI / EC: Add support to skip boot stage DSDT probe
We prepared _INI/_STA methods for \_SB, \_SB.PCI0, \_SB.LID0 and
\_SB.EC, _HID(PNP0C09)/_CRS/_GPE for \_SB.EC to poke Windows behavior
with qemu, we got the following execution sequence:
\_SB._INI
\_SB.PCI0._STA
\_SB.LID0._STA
\_SB.EC._STA
\_SB.PCI0._INI
\_SB.LID0._INI
\_SB.EC._INI
There is no extra DSDT EC device enumeration process occurring before
the main ACPI device enumeration process. That means acpi_ec_dsdt_probe()
is not Windows-compatible.
Tracking back, it was added by the following commit:
Commit: c5279dee26c0e8d7c4200993bfc4b540d2469598
Subject: ACPI: EC: Add some basic check for ECDT data
but that commit was misguided.
Why we shouldn't enumerate DSDT EC before the main ACPI device
enumeration?
The only way to know if the DSDT EC is valid would be to evaluate its
_STA control method, but it's not safe to evaluate this control method
that early and out of the ACPI enumeration process, because _STA may
refer to entities (such as resources or ACPI device objects) that may
not have been initialized before OSPM starts to enumerate them via
the main ACPI device enumeration.
But after we had reverted back to the expected behavior, a regression
was reported. On that platform, there is no ECDT, but the platform
control methods access EC operation region earlier than Linux expects
causing some ACPI method execution errors. For this reason, we just
go back to old behavior to still probe DSDT EC as the boot EC.
However, that turns out to lead to yet another functional breakage
and in order to work around all of the problems, we skip boot stage
DSDT probe when the ECDT exists so that a later quirk can always use
correct ECDT GPE setting.
Link: http://bugzilla.kernel.org/show_bug.cgi?id=11880
Link: http://bugzilla.kernel.org/show_bug.cgi?id=119261
Link: http://bugzilla.kernel.org/show_bug.cgi?id=195651
Tested-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog & comments massage ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-15 09:41:41 +08:00
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2016-06-03 10:26:12 +08:00
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2008-01-01 14:12:55 -05:00
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2016-06-03 10:26:12 +08:00
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2016-06-21 17:42:05 +08:00
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2016-06-03 10:26:12 +08:00
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ACPI / EC: Add support to skip boot stage DSDT probe
We prepared _INI/_STA methods for \_SB, \_SB.PCI0, \_SB.LID0 and
\_SB.EC, _HID(PNP0C09)/_CRS/_GPE for \_SB.EC to poke Windows behavior
with qemu, we got the following execution sequence:
\_SB._INI
\_SB.PCI0._STA
\_SB.LID0._STA
\_SB.EC._STA
\_SB.PCI0._INI
\_SB.LID0._INI
\_SB.EC._INI
There is no extra DSDT EC device enumeration process occurring before
the main ACPI device enumeration process. That means acpi_ec_dsdt_probe()
is not Windows-compatible.
Tracking back, it was added by the following commit:
Commit: c5279dee26c0e8d7c4200993bfc4b540d2469598
Subject: ACPI: EC: Add some basic check for ECDT data
but that commit was misguided.
Why we shouldn't enumerate DSDT EC before the main ACPI device
enumeration?
The only way to know if the DSDT EC is valid would be to evaluate its
_STA control method, but it's not safe to evaluate this control method
that early and out of the ACPI enumeration process, because _STA may
refer to entities (such as resources or ACPI device objects) that may
not have been initialized before OSPM starts to enumerate them via
the main ACPI device enumeration.
But after we had reverted back to the expected behavior, a regression
was reported. On that platform, there is no ECDT, but the platform
control methods access EC operation region earlier than Linux expects
causing some ACPI method execution errors. For this reason, we just
go back to old behavior to still probe DSDT EC as the boot EC.
However, that turns out to lead to yet another functional breakage
and in order to work around all of the problems, we skip boot stage
DSDT probe when the ECDT exists so that a later quirk can always use
correct ECDT GPE setting.
Link: http://bugzilla.kernel.org/show_bug.cgi?id=11880
Link: http://bugzilla.kernel.org/show_bug.cgi?id=119261
Link: http://bugzilla.kernel.org/show_bug.cgi?id=195651
Tested-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog & comments massage ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-15 09:41:41 +08:00
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2016-06-21 17:42:05 +08:00
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2016-06-03 10:26:12 +08:00
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2016-09-07 16:50:21 +08:00
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2016-06-03 10:26:12 +08:00
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2016-06-21 17:42:05 +08:00
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2008-01-01 14:12:55 -05:00
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2016-09-07 16:50:21 +08:00
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2016-06-21 17:42:05 +08:00
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2016-09-07 16:50:08 +08:00
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2016-06-21 17:42:05 +08:00
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2008-01-01 14:12:55 -05:00
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2016-09-07 16:50:21 +08:00
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2017-08-16 15:29:49 +08:00
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2016-09-07 16:50:21 +08:00
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2017-08-17 10:21:12 +08:00
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2016-09-07 16:50:21 +08:00
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2017-08-17 10:21:12 +08:00
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2016-09-07 16:50:21 +08:00
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2017-09-26 16:54:09 +08:00
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2016-09-07 16:50:21 +08:00
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ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.
It is reported that on several platforms, EC firmware will not respond
non-expected QR_EC (see EC_FLAGS_QUERY_HANDSHAKE, only write QR_EC when
SCI_EVT is set).
Unfortunately, ACPI specification doesn't define when the SCI_EVT should be
cleared by the firmware, thus the original implementation queued up second
QR_EC right after writing QR_EC command and before reading the returned
event value as at that time the SCI_EVT is ensured not cleared. This
behavior is also based on the assumption that the firmware should be able
to return 0x00 to indicate "no outstanding event". This behavior did fix
issues on Samsung platforms where the spurious query value of 0x00 is
supported and didn't break platforms in my test queue.
But recently, specific Acer, Asus, Lenovo platforms keep on blaming this
change.
This patch changes the behavior to re-check the SCI_EVT a bit later and
removes EC_FLAGS_QUERY_HANDSHAKE quirks, hoping this is the Windows
compliant EC driver behavior.
In order to be robust to the possible regressions, instead of removing the
quirk directly, this patch keeps the quirk code, removes the quirk users
and keeps old behavior for Samsung platforms.
Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
Link: https://bugzilla.kernel.org/show_bug.cgi?id=97381
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98111
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-and-tested-by: Tigran Gabrielyan <tigrangab@gmail.com>
Reported-and-tested-by: Adrien D <ghbdtn@openmailbox.org>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-06-11 13:21:45 +08:00
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2014-10-29 11:33:49 +08:00
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ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.
It is reported that on several platforms, EC firmware will not respond
non-expected QR_EC (see EC_FLAGS_QUERY_HANDSHAKE, only write QR_EC when
SCI_EVT is set).
Unfortunately, ACPI specification doesn't define when the SCI_EVT should be
cleared by the firmware, thus the original implementation queued up second
QR_EC right after writing QR_EC command and before reading the returned
event value as at that time the SCI_EVT is ensured not cleared. This
behavior is also based on the assumption that the firmware should be able
to return 0x00 to indicate "no outstanding event". This behavior did fix
issues on Samsung platforms where the spurious query value of 0x00 is
supported and didn't break platforms in my test queue.
But recently, specific Acer, Asus, Lenovo platforms keep on blaming this
change.
This patch changes the behavior to re-check the SCI_EVT a bit later and
removes EC_FLAGS_QUERY_HANDSHAKE quirks, hoping this is the Windows
compliant EC driver behavior.
In order to be robust to the possible regressions, instead of removing the
quirk directly, this patch keeps the quirk code, removes the quirk users
and keeps old behavior for Samsung platforms.
Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
Link: https://bugzilla.kernel.org/show_bug.cgi?id=97381
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98111
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-and-tested-by: Tigran Gabrielyan <tigrangab@gmail.com>
Reported-and-tested-by: Adrien D <ghbdtn@openmailbox.org>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-06-11 13:21:45 +08:00
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2014-10-29 11:33:49 +08:00
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ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.
It is reported that on several platforms, EC firmware will not respond
non-expected QR_EC (see EC_FLAGS_QUERY_HANDSHAKE, only write QR_EC when
SCI_EVT is set).
Unfortunately, ACPI specification doesn't define when the SCI_EVT should be
cleared by the firmware, thus the original implementation queued up second
QR_EC right after writing QR_EC command and before reading the returned
event value as at that time the SCI_EVT is ensured not cleared. This
behavior is also based on the assumption that the firmware should be able
to return 0x00 to indicate "no outstanding event". This behavior did fix
issues on Samsung platforms where the spurious query value of 0x00 is
supported and didn't break platforms in my test queue.
But recently, specific Acer, Asus, Lenovo platforms keep on blaming this
change.
This patch changes the behavior to re-check the SCI_EVT a bit later and
removes EC_FLAGS_QUERY_HANDSHAKE quirks, hoping this is the Windows
compliant EC driver behavior.
In order to be robust to the possible regressions, instead of removing the
quirk directly, this patch keeps the quirk code, removes the quirk users
and keeps old behavior for Samsung platforms.
Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
Link: https://bugzilla.kernel.org/show_bug.cgi?id=97381
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98111
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-and-tested-by: Tigran Gabrielyan <tigrangab@gmail.com>
Reported-and-tested-by: Adrien D <ghbdtn@openmailbox.org>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-06-11 13:21:45 +08:00
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2014-10-29 11:33:49 +08:00
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ACPI / EC: Remove wrong ECDT correction quirks
Our Windows probe result shows that EC._REG is evaluated after evaluating
all _INI/_STA control methods.
With boot EC always switched in acpi_ec_dsdt_probe(), we can see that as
long as there is no EC opregion accesses in the MLC (module level code, AML
code out of any control methods) and in _INI/_STA, there is no need to make
sure that ECDT must be correct.
Bugs of 9399/12461 were reported against an order issue that BAT0/1._STA
evaluations contain EC accesses while the ECDT setting is wrong.
>From the acpidump output posted on bug 9399, we can see that it is actually
a different issue. In this table, if EC._REG is not executed, EC accesses
will be done in a platform specific manner. As we've already ensured not to
execute EC._REG during the eary stage, we can remove the quirks for bug
9399.
From the acpidump output posted on bug 12461, we can see that it still
needs the quirk. In this table, EC._REG flags a named object whose default
value is One, thus BAT1._STA surely should invoke EC accesses whatever we
invoke EC._REG or not. We have to keep the quirk for it before we can root
cause the issue.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-21 17:42:12 +08:00
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ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
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2017-06-15 09:41:47 +08:00
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2017-06-15 09:41:53 +08:00
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2017-06-15 09:41:47 +08:00
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2017-09-14 11:59:30 +02:00
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ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
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2015-05-15 14:37:11 +08:00
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2017-06-15 09:41:47 +08:00
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2017-06-15 09:41:53 +08:00
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2017-06-15 09:41:47 +08:00
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2009-10-02 20:21:33 +04:00
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2005-08-11 17:32:05 -04:00
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2005-04-16 15:20:36 -07:00
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2016-06-21 17:42:05 +08:00
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2007-03-07 22:28:00 +03:00
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2016-06-21 17:42:05 +08:00
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2005-04-16 15:20:36 -07:00
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2016-06-21 17:42:05 +08:00
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2007-03-07 22:28:00 +03:00
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2009-10-02 20:21:33 +04:00
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2007-03-07 22:28:00 +03:00
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ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
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2016-06-21 17:42:05 +08:00
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ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
|
|
|
|
2016-06-21 17:42:05 +08:00
|
|
|
|
|
|
|
|
|
2007-08-03 17:52:48 -04:00
|
|
|
|
2016-06-21 17:42:05 +08:00
|
|
|
|
2016-09-07 16:50:21 +08:00
|
|
|
|
|
|
|
|
|
|
|
|
|
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|
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|
|
|
|
|
2008-11-26 17:11:53 -05:00
|
|
|
|
2016-06-21 17:42:05 +08:00
|
|
|
|
2016-09-07 16:50:08 +08:00
|
|
|
|
ACPI 2.0 / ECDT: Remove early namespace reference from EC
All operation region accesses are allowed by AML interpreter when AML is
executed, so actually BIOSen are responsible to avoid the operation region
accesses in AML before OSPM has prepared an operation region driver. This
is done via _REG control method. So AML code normally sets a global named
object REGC to 1 when _REG(3, 1) is evaluated.
Then what is ECDT? Quoting from ACPI spec 6.0, 5.2.15 Embedded Controller
Boot Resources Table (ECDT):
"The presence of this table allows OSPM to provide Embedded Controller
operation region space access before the namespace has been evaluated."
Spec also suggests a compatible mean to indicate the early EC access
availability:
Device (EC)
{
Name (REGC, Ones)
Method (_REG, 2)
{
If (LEqual (Arg0, 3))
{
Store (Arg1, REGC)
}
}
Method (ECAV)
{
If (LEqual (REGC, Ones))
{
If (LGreaterEqual (_REV, 2))
{
Return (One)
}
Else
{
Return (Zero)
}
}
Else
{
Return (REGC)
}
}
}
In this way, it allows EC accesses to happen before EC._REG(3, 1) is
invoked.
But ECAV is not the only way practical BIOSen using to indicate the early
EC access availibility, the known variations include:
1. Setting REGC to One in \_SB._INI when _REV >= 2. Since \_SB._INI is the
first control method evaluated by OSPM during the enumeration, this
allows EC accesses to happen for the entire enumeration process before
the namespace EC is enumerated.
2. Initialize REGC to One by default, this even allows EC accesses to
happen during the table loading.
Linux is now broken around ECDT support during the long term bug fixing
work because it has merged many wrong ECDT bug fixes (see details below).
Linux currently uses namespace EC's settings instead of ECDT settings when
ECDT is detected. This apparently will result in namespace walk and
_CRS/_GPE/_REG evaluations. Such stuffs could only happen after namespace
is ready, while ECDT is purposely to be used before namespace is ready.
The wrong bug fixing story is:
1. Link 1:
At Linux ACPI early stages, "no _Lxx/_Exx/_Qxx evaluation can happen
before the namespace is ready" are not ensured by ACPICA core and Linux.
This is currently ensured by deferred enabling of GPE and defered
registering of EC query methods (acpi_ec_register_query_methods).
2. Link 2:
Reporters reported buggy ECDTs, expecting quirks for the platform.
Originally, the quirk is simple, only doing things with ECDT.
Bug 9399 and 12461 are platforms (Asus L4R, Asus M6R, MSI MS-171F)
reported to have wrong ECDT IO port addresses, the port addresses are
reversed.
Bug 11880 is a platform (Asus X50GL) reported to have 0 valued port
addresses, we can see that all EC accesses are protected by ECAV on
this platform, so actually no early EC accesses is required by this
platform.
3. Link 3:
But when the bug fixing developer was requested to provide a handy and
non-quirk bug fix, he tried to use correct EC settings from namespace
and broke the spec purpose. We can even see that the developer was
suffered from many regrssions. One interesting one is 14086, where the
actual root cause obviously should be: _REG is evaluated too early. But
unfortunately, the bug is fixed in a totally wrong way.
So everything goes wrong from these commits:
Commit: c6cb0e878446c79f42e7833d7bb69ed6bfbb381f
Subject: ACPI: EC: Don't trust ECDT tables from ASUS
Commit: a5032bfdd9c80e0231a6324661e123818eb46ecd
Subject: ACPI: EC: Always parse EC device
This patch reverts Linux behavior to simple ECDT quirk support in order to
stop early _CRS/_GPE/_REG evaluations.
For Bug 9399, 12461, since it is reported that the platforms require early
EC accesses, this patch restores the simple ECDT quirks for them.
For Bug 11880, since it is not reported that the platform requires early EC
accesses and its ACPI tables contain correct ECAV, we choose an ECDT
enumeration failure for this platform.
Link 1: https://bugzilla.kernel.org/show_bug.cgi?id=9916
http://bugzilla.kernel.org/show_bug.cgi?id=10100
https://lkml.org/lkml/2008/2/25/282
Link 2: https://bugzilla.kernel.org/show_bug.cgi?id=9399
https://bugzilla.kernel.org/show_bug.cgi?id=12461
https://bugzilla.kernel.org/show_bug.cgi?id=11880
Link 3: https://bugzilla.kernel.org/show_bug.cgi?id=11884
https://bugzilla.kernel.org/show_bug.cgi?id=14081
https://bugzilla.kernel.org/show_bug.cgi?id=14086
https://bugzilla.kernel.org/show_bug.cgi?id=14446
Link 4: https://bugzilla.kernel.org/show_bug.cgi?id=112911
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-24 10:42:53 +08:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
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|
|
2016-08-03 09:07:58 +08:00
|
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|
|
ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
|
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|
ACPI / sleep: EC-based wakeup from suspend-to-idle on recent systems
Some recent Dell laptops, including the XPS13 model numbers 9360 and
9365, cannot be woken up from suspend-to-idle by pressing the power
button which is unexpected and makes that feature less usable on
those systems. Moreover, on the 9365 ACPI S3 (suspend-to-RAM) is
not expected to be used at all (the OS these systems ship with never
exercises the ACPI S3 path in the firmware) and suspend-to-idle is
the only viable system suspend mechanism there.
The reason why the power button wakeup from suspend-to-idle doesn't
work on those systems is because their power button events are
signaled by the EC (Embedded Controller), whose GPE (General Purpose
Event) line is disabled during suspend-to-idle transitions in Linux.
That is done on purpose, because in general the EC tends to be noisy
for various reasons (battery and thermal updates and similar, for
example) and all events signaled by it would kick the CPUs out of
deep idle states while in suspend-to-idle, which effectively might
defeat its purpose.
Of course, on the Dell systems in question the EC GPE must be enabled
during suspend-to-idle transitions for the button press events to
be signaled while suspended at all, but fortunately there is a way
out of this puzzle.
First of all, those systems have the ACPI_FADT_LOW_POWER_S0 flag set
in their ACPI tables, which means that the OS is expected to prefer
the "low power S0 idle" system state over ACPI S3 on them. That
causes the most recent versions of other OSes to simply ignore ACPI
S3 on those systems, so it is reasonable to expect that it should not
be necessary to block GPEs during suspend-to-idle on them.
Second, in addition to that, the systems in question provide a special
firmware interface that can be used to indicate to the platform that
the OS is transitioning into a system-wide low-power state in which
certain types of activity are not desirable or that it is leaving
such a state and that (in principle) should allow the platform to
adjust its operation mode accordingly.
That interface is a special _DSM object under a System Power
Management Controller device (PNP0D80). The expected way to use it
is to invoke function 0 from it on system initialization, functions
3 and 5 during suspend transitions and functions 4 and 6 during
resume transitions (to reverse the actions carried out by the
former). In particular, function 5 from the "Low-Power S0" device
_DSM is expected to cause the platform to put itself into a low-power
operation mode which should include making the EC less verbose (so to
speak). Next, on resume, function 6 switches the platform back to
the "working-state" operation mode.
In accordance with the above, modify the ACPI suspend-to-idle code
to look for the "Low-Power S0" _DSM interface on platforms with the
ACPI_FADT_LOW_POWER_S0 flag set in the ACPI tables. If it's there,
use it during suspend-to-idle transitions as prescribed and avoid
changing the GPE configuration in that case. [That should reflect
what the most recent versions of other OSes do.]
Also modify the ACPI EC driver to make it handle events during
suspend-to-idle in the usual way if the "Low-Power S0" _DSM interface
is going to be used to make the power button events work while
suspended on the Dell machines mentioned above
Link: http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-23 15:24:32 +02:00
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ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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ACPI / EC: Add parameter to force disable the GPE on suspend
After commit 8110dd281e15 (ACPI / sleep: EC-based wakeup from
suspend-to-idle on recent systems) the configuration of GPEs,
including the EC one, is not changed during suspend-to-idle on
recent systems. That's in order to make system wakeup events
generated by the EC work, in particular.
However, on some of the systems in question (for example on Dell
XPS13 9365), in addition to generating system wakeup events the
EC generates a heartbeat sequence of interrupts that have nothing
to do with wakeup while suspended, and the Low Power Idle S0 _DSM
interface doesn't change that behavior.
The users of those systems may prefer to disable the EC GPE during
system suspend, for the cost of non-functional power button wakeup
or similar, but currently there is no way to do that.
For this reason, add a new module parameter, ec_no_wakeup, for the
EC driver module that, if set, will cause the EC GPE to be disabled
during system suspend and re-enabled during the subsequent system
resume.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=192591#c106
Amends: 8110dd281e15 (ACPI / sleep: EC-based wakeup from suspend-to-idle on recent systems)
Reported-and-tested-by: Patrik Kullman <patrik.kullman@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-19 14:41:58 +02:00
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ACPI / EC: Add PM operations to improve event handling for resume process
This patch makes 2 changes:
1. Restore old behavior
Originally, EC driver stops handling both events and transactions in
acpi_ec_block_transactions(), and restarts to handle transactions in
acpi_ec_unblock_transactions_early(), restarts to handle both events and
transactions in acpi_ec_unblock_transactions().
While currently, EC driver still stops handling both events and
transactions in acpi_ec_block_transactions(), but restarts to handle both
events and transactions in acpi_ec_unblock_transactions_early().
This patch tries to restore the old behavior by dropping
__acpi_ec_enable_event() from acpi_unblock_transactions_early().
2. Improve old behavior
However this still cannot fix the real issue as both of the
acpi_ec_unblock_xxx() functions are invoked in the noirq stage. Since the
EC driver actually doesn't implement the event handling in the polling
mode, re-enabling the event handling too early in the noirq stage could
result in the problem that if there is no triggering source causing
advance_transaction() to be invoked, pending SCI_EVT cannot be detected by
the EC driver and _Qxx cannot be triggered.
It actually makes sense to restart the event handling in any point during
resuming after the noirq stage. Just like the boot stage where the event
handling is enabled in .add(), this patch further moves
acpi_ec_enable_event() to .resume(). After doing that, the following 2
functions can be combined:
acpi_ec_unblock_transactions_early()/acpi_ec_unblock_transactions().
The differences of the event handling availability between the old behavior
(this patch isn't applied) and the new behavior (this patch is applied) are
as follows:
!Applied Applied
before suspend Y Y
suspend before EC Y Y
suspend after EC Y Y
suspend_late Y Y
suspend_noirq Y (actually N) Y (actually N)
resume_noirq Y (actually N) Y (actually N)
resume_late Y (actually N) Y (actually N)
resume before EC Y (actually N) Y (actually N)
resume after EC Y (actually N) Y
after resume Y (actually N) Y
Where "actually N" means if there is no triggering source, the EC driver
is actually not able to notice the pending SCI_EVT occurred in the noirq
stage. So we can clearly see that this patch has improved the situation.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:36 +08:00
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2016-08-03 09:07:58 +08:00
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ACPI / EC: Add parameter to force disable the GPE on suspend
After commit 8110dd281e15 (ACPI / sleep: EC-based wakeup from
suspend-to-idle on recent systems) the configuration of GPEs,
including the EC one, is not changed during suspend-to-idle on
recent systems. That's in order to make system wakeup events
generated by the EC work, in particular.
However, on some of the systems in question (for example on Dell
XPS13 9365), in addition to generating system wakeup events the
EC generates a heartbeat sequence of interrupts that have nothing
to do with wakeup while suspended, and the Low Power Idle S0 _DSM
interface doesn't change that behavior.
The users of those systems may prefer to disable the EC GPE during
system suspend, for the cost of non-functional power button wakeup
or similar, but currently there is no way to do that.
For this reason, add a new module parameter, ec_no_wakeup, for the
EC driver module that, if set, will cause the EC GPE to be disabled
during system suspend and re-enabled during the subsequent system
resume.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=192591#c106
Amends: 8110dd281e15 (ACPI / sleep: EC-based wakeup from suspend-to-idle on recent systems)
Reported-and-tested-by: Patrik Kullman <patrik.kullman@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-19 14:41:58 +02:00
|
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|
ACPI / EC: Add PM operations to improve event handling for suspend process
In the original EC driver, though the event handling is not explicitly
stopped, the EC driver is actually not able to handle events during the
noirq stage as the EC driver is not prepared to handle the EC events in the
polling mode. So if there is no advance_transaction() triggered, the EC
driver couldn't notice the EC events.
However, do we actually need to handle EC events during suspend/resume
stage? EC events are mostly useless for the suspend/resume period (key
strokes and battery/thermal updates, etc.,), and the useful ones (lid
close, power/sleep button press) should have already been delivered to the
OSPM to trigger the power saving operations.
Thus this patch implements acpi_ec_disable_event() to be a reverse call of
acpi_ec_enable_event(), with which, the EC driver is able to stop handling
the EC events in a position before entering the noirq stage.
Since there are actually 2 choices for us:
1. implement event handling in polling mode;
2. stop event handling before entering noirq stage.
And this patch only implements the second choice using .suspend() callback.
Thus this is experimental (first choice is better? or different hook
position is better?). This patch finally keeps the old behavior by default
and prepares a boot parameter to enable this feature.
The differences of the event handling availability between the old behavior
(this patch is not applied) and the new behavior (this patch is applied)
are as follows:
!FreezeEvents FreezeEvents
before suspend Y Y
suspend before EC Y Y
suspend after EC Y N
suspend_late Y N
suspend_noirq Y (actually N) N
resume_noirq Y (actually N) N
resume_late Y (actually N) N
resume before EC Y (actually N) N
resume after EC Y Y
after resume Y Y
Where "actually N" means if there is no EC transactions, the EC driver
is actually not able to notice the pending events.
We can see that FreezeEvents is the only approach now can actually flush
the EC event handling with both query commands and _Qxx evaluations
flushed, other modes can only flush the EC event handling with only query
commands flushed, _Qxx evaluations occurred after stopping the EC driver
may end up failure due to the failure of the EC transaction carried out in
the _Qxx control methods.
We also can see that this feature should be able to trigger some platform
notifications later than resuming other drivers.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-03 16:01:43 +08:00
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2016-08-03 09:07:58 +08:00
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2015-06-11 13:21:38 +08:00
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2008-03-21 17:07:21 +03:00
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2016-08-03 09:07:58 +08:00
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2008-03-21 17:07:21 +03:00
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2016-08-03 09:00:14 +08:00
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2009-03-24 16:49:48 -06:00
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2005-04-16 15:20:36 -07:00
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2016-08-03 09:00:14 +08:00
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2017-08-16 15:29:49 +08:00
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2005-04-16 15:20:36 -07:00
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2016-08-03 09:00:14 +08:00
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2017-08-16 15:29:49 +08:00
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2005-04-16 15:20:36 -07:00
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2017-08-16 15:29:49 +08:00
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2017-09-26 16:54:09 +08:00
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2017-08-17 10:21:12 +08:00
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2017-08-16 15:29:49 +08:00
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2005-04-16 15:20:36 -07:00
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2005-08-11 17:32:05 -04:00
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2005-04-16 15:20:36 -07:00
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2016-08-03 09:00:14 +08:00
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2005-04-16 15:20:36 -07:00
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2007-10-22 14:18:43 +04:00
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