linux-kernel - Re: [PATCH v5 7/7] Documentation:cpufreq:boost: Update BOOST documentation

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Date:	Wed, 17 Jul 2013 09:36:14 +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 7/7] Documentation:cpufreq:boost: Update BOOST
 documentation

On Wed, 17 Jul 2013 10:52:18 +0530 Viresh Kumar viresh.kumar@...aro.org
wrote,
> On 16 July 2013 17:03, Lukasz Majewski <l.majewski@...sung.com> wrote:
> > As fair as I've understood our previous discussion (at [*]) we have
> > agreed about this. We only export boost attribute when it is
> > supported by cpufreq_driver. Rafael was very clear about exporting
> > boost attribute:
> >
> > "Simple: Export it only when supported."
> >
> > [*]: Re: [PATCH v4 2/7] cpufreq: Add boost frequency support in core
> 
> I don't want to search in the Archives but I am sure what we decided
> earlier.

At v4 there was the old acpi-cpufreq.c behaviour preserved (with always
exporting boost - when not supported ro, when supported rw).

Due to Rafael and Dirk comments it has been rewritten at v5:

http://thread.gmane.org/gmane.linux.kernel/1511831/match=patch+v4+2+7+cpufreq+add+boost+frequency+support+core


> 
> Rafael Said:
> "Simple: Export it only when supported."
              [*]

> 
> AND
> 
> "Don't change behavior of acpi-cpufreq driver" 
              [**]
> 
> If you see acpi-cpufreq driver carefully, it always creates "boost"
> sysfs entry. If its not supported then it creates a read only entry.

For me those two statements [*] and [**] contradict:

At v5:
1. ARM - export "boost" only when supported (rw)
2. x86 - export boost only when x86 supports it (as rw). When x86
	 doesn't support HW boost - DO NOT export it at all.

At v4:
1. ARM - export "boost" only when supported (rw)
2. x86 - always export boost - no matter if supported or not. If not
	 supported, then export it as ro only.


> 
> So, please preserve that.


-- 
Best regards,

Lukasz Majewski

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