linux-kernel - Re: [PATCH v6 0/8] cpufreq:boost: CPU Boost mode support

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Message-ID: <CAKohpokTqL8QPFrM9OQJvC78iM92XR+KOkFSZXpWzesa7Uc9sA@mail.gmail.com>
Date:	Fri, 26 Jul 2013 15:58:49 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Lukasz Majewski <l.majewski@...sung.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <eduardo.valentin@...com>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	Lukasz Majewski <l.majewski@...ess.pl>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>, durgadoss.r@...el.com
Subject: Re: [PATCH v6 0/8] cpufreq:boost: CPU Boost mode support

On 25 July 2013 22:03, Lukasz Majewski <l.majewski@...sung.com> 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..
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