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Marek Behún a13b110e7c cpufreq: armada-37xx: Fix setting TBG parent for load levels 
[ Upstream commit 22592df194 ]

With CPU frequency determining software [1] we have discovered that
after this driver does one CPU frequency change, the base frequency of
the CPU is set to the frequency of TBG-A-P clock, instead of the TBG
that is parent to the CPU.

This can be reproduced on EspressoBIN and Turris MOX:
  cd /sys/devices/system/cpu/cpufreq/policy0
  echo powersave >scaling_governor
  echo performance >scaling_governor

Running the mhz tool before this driver is loaded reports 1000 MHz, and
after loading the driver and executing commands above the tool reports
800 MHz.

The change of TBG clock selector is supposed to happen in function
armada37xx_cpufreq_dvfs_setup. Before the function returns, it does
this:
  parent = clk_get_parent(clk);
  clk_set_parent(clk, parent);

The armada-37xx-periph clock driver has the .set_parent method
implemented correctly for this, so if the method was actually called,
this would work. But since the introduction of the common clock
framework in commit b2476490ef ("clk: introduce the common clock..."),
the clk_set_parent function checks whether the parent is actually
changing, and if the requested new parent is same as the old parent
(which is obviously the case for the code above), the .set_parent method
is not called at all.

This patch fixes this issue by filling the correct TBG clock selector
directly in the armada37xx_cpufreq_dvfs_setup during the filling of
other registers at the same address. But the determination of CPU TBG
index cannot be done via the common clock framework, therefore we need
to access the North Bridge Peripheral Clock registers directly in this
driver.

[1] https://github.com/wtarreau/mhz

Signed-off-by: Marek Behún <kabel@kernel.org>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Tested-by: Pali Rohár <pali@kernel.org>
Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Tested-by: Anders Trier Olesen <anders.trier.olesen@gmail.com>
Tested-by: Philip Soares <philips@netisense.com>
Fixes: 92ce45fb87 ("cpufreq: Add DVFS support for Armada 37xx")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2021-05-14 09:50:17 +02:00
arch m68k: mvme147,mvme16x: Don't wipe PCC timer config bits 2021-05-14 09:50:14 +02:00
block block: return -EBUSY when there are open partitions in blkdev_reread_part 2021-04-28 13:39:59 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 11:37:59 +01:00
crypto async_xor: increase src_offs when dropping destination page 2021-05-14 09:49:59 +02:00
Documentation dt-bindings: serial: stm32: Use 'type: object' instead of false for 'additionalProperties' 2021-05-14 09:50:12 +02:00
drivers cpufreq: armada-37xx: Fix setting TBG parent for load levels 2021-05-14 09:50:17 +02:00
fs NFSv4.2: fix copy stateid copying for the async copy 2021-05-14 09:50:13 +02:00
include PM: runtime: Replace inline function pm_runtime_callbacks_present() 2021-05-14 09:50:16 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:36:11 +02:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel tracing: Restructure trace_clock_global() to never block 2021-05-11 14:47:40 +02:00
lib crypto: poly1305 - fix poly1305_core_setkey() declaration 2021-05-14 09:50:13 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: ptdump: fix build failure 2021-04-21 13:00:57 +02:00
net cfg80211: scan: drop entry from hidden_list on overflow 2021-05-14 09:50:00 +02:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:06:12 +01:00
scripts kasan: fix hwasan build for gcc 2021-04-28 13:40:02 +02:00
security selinux: add proper NULL termination to the secclass_map permissions 2021-05-14 09:49:59 +02:00
sound ALSA: hda/realtek: Fix speaker amp on HP Envy AiO 32 2021-05-14 09:50:03 +02:00
tools Revert "tools/power turbostat: adjust for temperature offset" 2021-05-14 09:50:05 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Stop looking for coalesced MMIO zones if the bus is destroyed 2021-05-14 09:50:04 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: move the staging subsystem to lists.linux.dev 2021-03-25 09:04:18 +01:00
Makefile Linux 5.10.36 2021-05-11 14:47:41 +02:00
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.