linux-kernel - Re: [PATCH] cpufreq: cpufreq-cpu0: No need to check cpu number in init()

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Date:	Mon, 1 Apr 2013 14:44:20 +0800
From:	Shawn Guo <shawn.guo@...aro.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	<rjw@...k.pl>, <cpufreq@...r.kernel.org>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linaro-kernel@...ts.linaro.org>, <patches@...aro.org>,
	<robin.randhawa@....com>, <Steve.Bannister@....com>,
	<Liviu.Dudau@....com>, <charles.garcia-tobin@....com>,
	<arvind.chauhan@....com>
Subject: Re: [PATCH] cpufreq: cpufreq-cpu0: No need to check cpu number in
 init()

On Sat, Mar 30, 2013 at 06:26:29PM +0530, Viresh Kumar wrote:
> It is not possible for init() to be called for any cpu other than cpu0. During
> bootup whatever cpu is used to boot system will be assigned as cpu0. And later
> on policy->cpu can only change if we hotunplug all cpus first and then hotplug
> them back in different order, which isn't possible (system requires atleast one
> cpu to be up always :)).
> 
> Though I can see one situation where policy->cpu can be different then zero.
> - Hot-unplug cpu 0.
> - rmmod cpufreq-cpu0 module
> - insmod it back
> - hotplug cpu 0 again.
> 
> Here, policy->cpu would be different. But the driver doesn't have any dependency
> on cpu0 as such. We don't mind which cpu of a system is policy->cpu and so this
> check is just not required.
> 
> Remove it.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

Acked-by: Shawn Guo <shawn.guo@...aro.org>

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