linux-kernel - Re: [PATCH v5 6/7] cpufreq:boost:Kconfig: Enable software managed BOOST support at Kconfig

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Date:	Wed, 17 Jul 2013 09:17:06 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
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>, l.majewski@...ess.pl,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andre Przywara <andre.przywara@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>
Subject: Re: [PATCH v5 6/7] cpufreq:boost:Kconfig: Enable software managed
 BOOST support at Kconfig

On Wed, 17 Jul 2013 10:54:55 +0530 Viresh Kumar viresh.kumar@...aro.org
wrote,
> On 16 July 2013 17:20, Lukasz Majewski <l.majewski@...sung.com> wrote:
> > On Tue, 16 Jul 2013 15:28:40 +0530 Viresh Kumar
> > viresh.kumar@...aro.org wrote,
> >> On 4 July 2013 14:20, Lukasz Majewski <l.majewski@...sung.com>
> >> wrote:
> >> > diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> >>
> >> > +config CPU_FREQ_BOOST_SW
> >> > +       bool "CPU frequency overclocking (BOOST)"
> >>
> >> Name it "CPU Frequency Overclocking - Software"
> >
> > Thanks, I had a puzzle to came up with a good short name :-).
> >
> >>
> >> > +       depends on ARM_EXYNOS_CPUFREQ && EXYNOS_THERMAL
> >                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [*]
> >>
> >> Remote Exynos from here. If you want to enable it for your
> >> platform by default, then select it from EXYNOS.

I can change ARM_EXYNOS_CPUFREQ -> CPUFREQ at [*]

> 
> I misread it a bit. I wanted to say make it dependent only on THERMAL
> and not on Exynos.

The cpufreq boost feature is possible to be enabled only when those [*]
dependencies are met. Moreover, it is disabled by default. 

This means that not only THERMAL generic code must be supported, but
also EXYNOS specific one - like per SoC trip points [**].

With thermal it is possible (and correct) to only define THERMAL, with
no platform (in this case Exynos) specific definitions. To force
potential user to define [**], I think, that EXYNOS_THERMAL is required.

> 
> > The purpose of the condition [*] here is to prevent from enabling
> > boost when thermal for Exynos is not supported.
> 
> Why? Can't others use it? Its not exynos specific :)

No it is not exynos specific.
For other platform one need to define:

depends on CPUFREQ && (EXYNOS_THERMAL || <PLATFORM_SUPPORTED>_THERMAL)

Such condition improves my confidence about proper boost usage.


-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
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