linux-kernel - Re: [PATCH 3/3] cpufreq: Remove unnecessary use of policy->shared

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Date:	Fri, 1 Feb 2013 12:43:12 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Santosh Shilimkar <santosh.shilimkar@...com>
Cc:	rjw@...k.pl, cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org,
	robin.randhawa@....com, Steve.Bannister@....com,
	Liviu.Dudau@....com, Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [PATCH 3/3] cpufreq: Remove unnecessary use of policy->shared_type

On 1 February 2013 12:17, Santosh Shilimkar <santosh.shilimkar@...com> wrote:
> I haven't looked at the cpufreq code recently but remember
> that it was needed to ensure that all the CPU which
> share clock/voltage gets updated (affected cpus) on
> freq change. The CPUs which needs SW co-ordination, should
> have this flag enabled and OMAP was falling in that category.

Freq change are done by the target routines of platform cpufreq drivers
and they do something like:

	for_each_cpu(freqs.cpu, policy->cpus)
		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

The only requirement from cpufreq core is to keep cpus sharing clock
in policy->cpus.

> May be I miss-understood its use, but can you confirm that
> SW co-ordination logic continues to work without this flag ?

I believe it should work. It works for the systems i worked on:

SPEAr13xx: Dual Cortex A9
ARM TC2: two clusters of A15s and A7s.
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