linux-kernel - Re: [Query] CPUFreq: Does these machines have separate clock domains for CPUs?

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Message-ID: <CANqRtoQF8-W=EFcV+LEPGbJf=h_yfyjVg=+0F5Sif15jB8XjBg@mail.gmail.com>
Date:	Wed, 4 Sep 2013 16:27:37 +0900
From:	Magnus Damm <magnus.damm@...il.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	Eric Miao <eric.y.miao@...il.com>, linux-cris-kernel@...s.com,
	SH-Linux <linux-sh@...r.kernel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Miao Steven <realmz6@...il.com>, Sekhar Nori <nsekhar@...com>,
	Mikael Starvik <starvik@...s.com>,
	Paul Mundt <lethal@...ux-sh.org>, sparclinux@...r.kernel.org,
	Dave Jones <davej@...hat.com>,
	David Miller <davem@...emloft.net>,
	John Crispin <blogic@...nwrt.org>
Subject: Re: [Query] CPUFreq: Does these machines have separate clock domains
 for CPUs?

Hi Viresh,

On Fri, Aug 30, 2013 at 4:33 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> On 30 August 2013 12:18, Magnus Damm <magnus.damm@...il.com> wrote:
>> Hi Viresh,
>>
>> On Thu, Aug 29, 2013 at 7:15 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>>> Hi,
>>>
>>> I have been doing some CPUFreq cleanup work and
>>> wanted to know if the below mentioned machines have separate
>>> clock domains for their CPUs or all share the same domain?
>>>
>>> So, that we can use some generic routines for these drivers which
>>> would eventually do:
>>>
>>> cpumask_setall(policy->cpus);
>>>
>>> And I wanted to make sure that this doesn't break them.. :)
>>>
>>> ......
>>>
>>> The drivers are:
>> ...
>>> drivers/cpufreq/sh-cpufreq.c
>> ...
>>
>> The above SH cpufreq driver seems to be written with SMP in mind, but
>> I would say SMP is a very rare case for SH. So I believe it can be
>> considered as UP-only at this point. If Paul disagrees I'm quite sure
>> he will tell us.
>
> Okay.. The problem isn't really SMP but different clock domains for CPUs
> in a SMP system..
>
> So, even if we have a SMP SH machine, will it have same clock line for
> all CPUs?

Yeah, I understand your question but I'm afraid that I don't know the
answer myself.

> I will go with the change anyway..

Good plan. Thanks for cleaning up the cpufreq bits.

Cheers,

/ magnus
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