linux-kernel - [PATCH V4 0/3] cpufreq: Allow default governor on cmdline and fix locking issues

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Message-Id: <cover.1593418662.git.viresh.kumar@linaro.org>
Date:   Mon, 29 Jun 2020 13:54:57 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>, Arnd Bergmann <arnd@...db.de>,
        Ben Segall <bsegall@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-pm@...r.kernel.org, kernel-team@...roid.com,
        tkjos@...gle.com, adharmap@...eaurora.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Quentin Perret <qperret@...gle.com>
Subject: [PATCH V4 0/3] cpufreq: Allow default governor on cmdline and fix locking issues

Hi,

I have picked Quentin's series over my patch, modified both and tested.

V3->V4:
- Do __module_get() for cpufreq_default_governor() case as well and get
  rid of an extra variable.
- Use a single character array, default_governor, instead of two of them.

V2->V3:
- default_governor is a string now and we don't set it on governor
  registration or unregistration anymore.
- Fixed locking issues in cpufreq_init_policy().

--
Viresh

Original cover letter fro Quentin:

This series enables users of prebuilt kernels (e.g. distro kernels) to
specify their CPUfreq governor of choice using the kernel command line,
instead of having to wait for the system to fully boot to userspace to
switch using the sysfs interface. This is helpful for 2 reasons:
  1. users get to choose the governor that runs during the actual boot;
  2. it simplifies the userspace boot procedure a bit (one less thing to
     worry about).

To enable this, the first patch moves all governor init calls to
core_initcall, to make sure they are registered by the time the drivers
probe. This should be relatively low impact as registering a governor
is a simple procedure (it gets added to a llist), and all governors
already load at core_initcall anyway when they're set as the default
in Kconfig. This also allows to clean-up the governors' init/exit code,
and reduces boilerplate.

The second patch introduces the new command line parameter, inspired by
its cpuidle counterpart. More details can be found in the respective
patch headers.

Changes in v2:
 - added Viresh's ack to patch 01
 - moved the assignment of 'default_governor' in patch 02 to the governor
   registration path instead of the driver registration (Viresh)

Quentin Perret (2):
  cpufreq: Register governors at core_initcall
  cpufreq: Specify default governor on command line

Viresh Kumar (1):
  cpufreq: Fix locking issues with governors

 .../admin-guide/kernel-parameters.txt         |  5 ++
 Documentation/admin-guide/pm/cpufreq.rst      |  6 +-
 .../platforms/cell/cpufreq_spudemand.c        | 26 +-----
 drivers/cpufreq/cpufreq.c                     | 87 ++++++++++++-------
 drivers/cpufreq/cpufreq_conservative.c        | 22 ++---
 drivers/cpufreq/cpufreq_ondemand.c            | 24 ++---
 drivers/cpufreq/cpufreq_performance.c         | 14 +--
 drivers/cpufreq/cpufreq_powersave.c           | 18 +---
 drivers/cpufreq/cpufreq_userspace.c           | 18 +---
 include/linux/cpufreq.h                       | 14 +++
 kernel/sched/cpufreq_schedutil.c              |  6 +-
 11 files changed, 100 insertions(+), 140 deletions(-)

-- 
2.25.0.rc1.19.g042ed3e048af