linux-kernel - Re: [PATCH 1/2] cpufreq: Return error if ->get() failed in cpufreq_update

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Message-ID: <CAKohponVBFaZY2tE8kJ91Gtj9MdvFKzGgWPNWxi38Kg8q9YUug@mail.gmail.com>
Date:	Mon, 10 Mar 2014 13:37:45 +0800
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Pierre Ossman <pierre-list@...man.eu>
Subject: Re: [PATCH 1/2] cpufreq: Return error if ->get() failed in cpufreq_update_policy()

On 26 February 2014 13:15, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> On 26 February 2014 03:59, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>> Yes, what exactly do we need it for in the core?
>
> Its probably there to make things faster. We cache the value so that we
> don't go to the hardware to read/calculate that again. Isn't it?
>
> And we need to know current freq on many occasions. One of that is that
> many drivers need to know the relation between current and new freq before
> they can make the change. As they might need to play with volt regulators
> before or after the freq change. Also it is used mainly in our loops_per_jiffiy
> calculations.

Ping!!
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