On 25 July 2013 22:03, Lukasz Majewski [off-list ref] wrote:

This patch series introduces support for CPU overclocking technique
called Boost.

It is a follow up of a LAB governor proposal. Boost is a LAB component:
http://thread.gmane.org/gmane.linux.kernel/1484746/match=cpufreq

Boost unifies hardware based solution (e.g. Intel Nehalem) with
software oriented one (like the one done at Exynos).
For this reason cpufreq/freq_table code has been reorganized to include
common code.

Important design decisions:
- Boost related code is compiled-in unconditionally to cpufreq core and
  disabled by default. The cpufreq_driver is responsibile for setting
  boost_supported flag and providing set_boost callback(if HW support
  is needed). For software managed boost, special Kconfig flag -
  CONFIG_CPU_FREQ_BOOST_SW has been defined. It will be selected only
  when a target platform has thermal framework properly configured.

- struct cpufreq_driver has been extended with boost related fields:
        -- boost_supported - when driver supports boosting
        -- boost_enabled - boost state
        -- set_boost - callback to function, which is necessary to
           enable/disable boost

- Boost sysfs attribute (/sys/devices/system/cpu/cpufreq/boost) is visible
  _only_ when cpufreq driver supports Boost.

- No special spin_lock for Boost was created. The one from cpufreq core
  was reused.

- All available policies are now stored in a list.

- The Boost code doesn't rely on any policy. When boost state is changed,
  then the policy list is iterated and proper adjustements are done.

- To improve safety level, the thermal framework is also extended to disable
  software boosting, when thermal trip point is reached. Then it starts
  monitoring target temperature to evaluate if boost can be enabled
  again. This emulates behaviour similar to HW managed boost (like x86)

New patches for v6:
cpufreq:exynos4x12: Change L0 driver data to CPUFREQ_BOOST_FREQ

Tested at HW:
       Exynos 4412 3.11-rc1 Linux
       Intel Core i7-3770 3.11-rc1 Linux

I am done with review of this patchset now and should say pretty much
comfortable with it now..