linux-kernel - Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock

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Message-ID: <CAKohpokMFwvY-SMcuJf_C_gASQT-8tT8wRrQ6=YX7QQ0YwcgNg@mail.gmail.com>
Date:	Wed, 22 Jan 2014 12:13:01 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Li, Zhuangzhi" <zhuangzhi.li@...el.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"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>,
	"Liu, Chuansheng" <chuansheng.liu@...el.com>
Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using
 shared clock

On 22 January 2014 11:56, Li, Zhuangzhi <zhuangzhi.li@...el.com> wrote:
> I don't think it's a real bug in bootloader, the bootloader can set CPUs to different frequencies according to actually requirements(Power saving first or Performance first),
> the CPUs freq policy are initialized in kernel, if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs frequencies aligned first,
> don't depend on the bootloader CPUs Pre-states, then the kernel can have better compatibility.
>
> If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these:
> 1. If all CPUs are in the same P-state, it does nothing when cpufreq registering
> 2. If the CPUs are in different P-states, all the other CPUs are aligned once to current frequency of CPU0 according to the present policy.

I thought, as you are asking kernel to keep same freq on all of them,
then same should be true for bootloaders.

Otherwise it was okay.
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