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Russell King - ARM Linux f058a86e71 ARM: dts: Fix OMAP4430 SDP Ethernet startup 
[ Upstream commit 84fb6c7feb ]

It was noticed that unbinding and rebinding the KSZ8851 ethernet
resulted in the driver reporting "failed to read device ID" at probe.
Probing the reset line with a 'scope while repeatedly attempting to
bind the driver in a shell loop revealed that the KSZ8851 RSTN pin is
constantly held at zero, meaning the device is held in reset, and
does not respond on the SPI bus.

Experimentation with the startup delay on the regulator set to 50ms
shows that the reset is positively released after 20ms.

Schematics for this board are not available, and the traces are buried
in the inner layers of the board which makes tracing where the RSTN pin
extremely difficult.  We can only guess that the RSTN pin is wired to a
reset generator chip driven off the ethernet supply, which fits the
observed behaviour.

Include this delay in the regulator startup delay - effectively
treating the reset as a "supply stable" indicator.

This can not be modelled as a delay in the KSZ8851 driver since the
reset generation is board specific - if the RSTN pin had been wired to
a GPIO, reset could be released earlier via the already provided support
in the KSZ8851 driver.

This also got confirmed by Peter Ujfalusi <peter.ujfalusi@ti.com> based
on Blaze schematics that should be very close to SDP4430:

TPS22902YFPR is used as the regulator switch (gpio48 controlled):
Convert arm boot_lock to raw The VOUT is routed to TPS3808G01DBV.
(SCH Note: Threshold set at 90%. Vsense: 0.405V).

According to the TPS3808 data sheet the RESET delay time when Ct is
open (this is the case in the schema): MIN/TYP/MAX: 12/20/28 ms.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
[tony@atomide.com: updated with notes from schematics from Peter]
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2019-02-12 20:02:16 +01:00
arch ARM: dts: Fix OMAP4430 SDP Ethernet startup 2019-02-12 20:02:16 +01:00
block block: use rcu_work instead of call_rcu to avoid sleep in softirq 2019-01-22 21:09:57 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: aes_ti - disable interrupts while accessing S-box 2019-02-12 20:02:06 +01:00
Documentation mm, proc: be more verbose about unstable VMA flags in /proc/<pid>/smaps 2019-01-26 09:20:51 +01:00
drivers media: v4l2-device: Link subdevices to their parent devices if available 2019-02-12 20:02:16 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs nfsd4: fix crash on writing v4_end_grace before nfsd startup 2019-02-12 20:02:12 +01:00
include RDMA/core: Sync unregistration with netlink commands 2019-02-12 20:02:10 +01:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-22 21:09:54 +01:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel kobject: return error code if writing /sys/.../uevent fails 2019-02-12 20:02:15 +01:00
lib fix int_sqrt64() for very large numbers 2019-01-22 21:09:55 +01:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm mm: migrate: don't rely on __PageMovable() of newpage after unlocking it 2019-02-06 17:27:44 +01:00
net tipc: fix node keep alive interval calculation 2019-02-12 20:02:15 +01:00
samples samples: bpf: fix: error handling regarding kprobe_events 2019-01-26 09:20:42 +01:00
scripts modpost: validate symbol names also in find_elf_symbol 2019-02-12 20:02:09 +01:00
security smack: fix access permissions for keyring 2019-02-12 20:02:14 +01:00
sound ASoC: Intel: mrfld: fix uninitialized variable access 2019-02-12 20:02:04 +01:00
tools perf tools: Add Hygon Dhyana support 2019-02-12 20:02:09 +01:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm/arm64: vgic: Fix off-by-one bug in vgic_get_irq() 2019-01-09 17:46:04 +01:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap mailmap: Update email for Punit Agrawal 2018-11-05 10:02:11 +00:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: update entry for MMP platform 2018-12-03 12:39:57 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-21 14:21:17 -08:00
Makefile Linux 4.20.7 2019-02-06 17:27:45 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.