linux-kernel - Re: [PATCH v2 1/3] cpufreq:boost: CPU frequency boost code unification for software and hardware solutions

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Message-ID: <2535901.EBhXeQ6J8O@vostro.rjw.lan>
Date:	Wed, 12 Jun 2013 13:23:20 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Lukasz Majewski <l.majewski@...sung.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Lukasz Majewski <l.majewski@...ess.pl>,
	Andre Przywara <andre.przywara@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>
Subject: Re: [PATCH v2 1/3] cpufreq:boost: CPU frequency boost code unification for software and hardware solutions

On Wednesday, June 12, 2013 09:39:38 AM Lukasz Majewski wrote:
> Hi Viresh,
> 
> > Hi,
> > 
> > Change subject to: "cpufreq: Add boost frequency support in core"
> 
> Ok.
> 
> > 
> > On 11 June 2013 14:33, Lukasz Majewski <l.majewski@...sung.com> wrote:
> > > This commit adds support for software based frequency boosting.
> > 
> > No. It adds support for both software and hardware boosting. So just
> > write: This commit adds boost frequency support in cpufreq core
> > (Hardware & Software).
> 
> Ok.
> > 
> > > Some SoC (like Exynos4 - e.g. 4x12) allow setting frequency above
> > > its normal condition limits. Such a change shall be only done for a
> > > short
> > 
> > s/condition/operation
> > s/change/mode
> > s/done/used
> > 
> 
> Ok.
> 
> > > time.
> > >
> > > Overclocking (boost) support is essentially provided by platform
> > > dependent cpufreq driver.
> > >
> > > This commit unifies support for SW and HW (Intel) over clocking
> > > solutions in the core cpufreq driver. Previously the "boost" sysfs
> > > attribute was defined at acpi driver code.
> > > By default boost is disabled. One global attribute is available at:
> > > /sys/devices/system/cpu/cpufreq/boost.
> > 
> > Enter a blank line here.
> 
> Ok
> 
> > 
> > > It only shows up when cpufreq driver supports overclocking.
> > > Under the hood frequencies dedicated for boosting are marked with a
> > > special flag (CPUFREQ_BOOST_FREQ) at driver's frequency table.
> > > It is the user's concern to enable/disable overclocking with proper
> > > call to sysfs.
> > 
> > Good.
> > 
> > > Signed-off-by: Lukasz Majewski <l.majewski@...sung.com>
> > > Signed-off-by: Myungjoo Ham <myungjoo.ham@...sung.com>
> > >
> > > --- 
>     ^^^^
> [*] this --- was added manually by me.
> 
> > > Changes for v2:
> > > - Removal of cpufreq_boost structure and move its fields to
> > > cpufreq_driver structure
> > > - Flag to indicate if global boost attribute is already defined
> > > - Extent the pr_{err|debbug} functions to show current function
> > > names ---
> > 
> > You don't have to manually add "---" here. Just keep a blank line
> > instead.
> 
> One "---" is added by git automatically. The [*] was added to distinct
> the changelog from rest of the commit. At least older versions of GIT
> required this to not include changelog to commit messages.

Which doesn't matter anyway.  None of them will show up in git log, so don't
worry. :-)

[...]

> 
> > And so we must have used
> > boost_en here.
> 
> boost_en has two meanings:
> 0 - either boost disabled or not supported (when low_level_boost=NULL).
> 1 - boost is enabled.

Gosh, please don't do that.  Use *two* flags, one meaning "supported" and the
second meaning "enabled".

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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