[0/2] cpufreq: Specify the default governor on command line

Message

Quentin Perret June 15, 2020, 4:55 p.m. UTC

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.

Feedback is very much welcome :-)

Thanks,
Quentin

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

 .../admin-guide/kernel-parameters.txt         |  5 +++
 Documentation/admin-guide/pm/cpufreq.rst      |  6 ++--
 .../platforms/cell/cpufreq_spudemand.c        | 26 ++------------
 drivers/cpufreq/cpufreq.c                     | 34 ++++++++++++++++---
 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, 73 insertions(+), 114 deletions(-)