linux-kernel - Re: [RFC v2 0/3][TESTS] LAB: Support for Legacy Application Booster governor

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Date:	Wed, 29 May 2013 15:45:23 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Vicent Guittot <vincent.guittot@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Lukasz Majewski <l.majewski@...ess.pl>
Subject: Re: [RFC v2 0/3][TESTS] LAB: Support for Legacy Application Booster
 governor - tests results

Hi Viresh,

> On 29 May 2013 12:39, Lukasz Majewski <l.majewski@...sung.com> wrote:
> > I also agree. Moreover, I think that there should be only one set of
> > "boost" sysfs entries either it is supported by HW (Intel) or SW
> > (ARM).
> 
> Yes, you need to change acpi-cpufreq driver too to use this common
> infrastructure.

Ok, thanks for pointing out.

> 
> > I can think of two "basic" one:
> > - max_turbo_freq (ro)
> 
> This is surely per policy as two separate clusters can have separate
> values. And probably a better one would be scaling_boost_frequencies,
> that will list all boost frequencies.

Ok,

> 
> > - turbo_mode/boost (rw)
> 
> I am confused with these two names: boost and turbo.. Probably we
> should use a single name everywhere. Because acpi-cpufreq is already
> using boost, we might shift to that.
> 
> > - /sys/devices/system/cpu/cpufreq/boost
> 
> Obviously this one.
> 
> > On the other hand first option would be used with systems, where
> > per-core (or core sets) frequency setting is possible (b.L,
> > Snapdragon S4)
> 
> For now this feature would be enabled on all clusters and controlled
> by cpu/cpufreq/boost.

This will simplify considerably the driver code.

> 
> > To sum up - the idea is as follow:
> >
> > 1. cpufreq_driver exports turbo_mode=1 when it supports overclocking
> > (this support can be hardcoded or read from device tree)
> >
> > 2. Then proper entries are exported to sysfs.
> >
> > 3. User via sysfs (at [*]) can enable/disable the feature on demand
> 
> Bingo!!

Thanks for suggestions. I'm now working on a prototype code. I plan to
post it at the beginning of next week.

-- 
Best regards,

Lukasz Majewski

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