Re: [PATCH] cpufreq: suspend/resume governors with PM notifiers
From: Viresh Kumar
Date: Thu Nov 21 2013 - 11:17:27 EST
On 21 November 2013 20:08, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Wednesday, November 20, 2013 11:04:28 AM Viresh Kumar wrote:
>> On 18 November 2013 11:09, viresh kumar <viresh.kumar@xxxxxxxxxx> wrote:
>> > Because in our usecase, we just want to know when suspend has started or
>> > resume has finished. And so we really don't need a per cpu callback.
>
> But it won't hurt I suppose?
Hmm.. getting a single call to cpufreq core would be faster for sure. Otherwise
we need to mark all the calls leaving the first one as no-ops..
> That actually isn't correct. On systems with ACPI the processor driver binds to
> those devices. So the processor driver could use PM callbacks on those systems
> in principle.
> Introduce proper drivers for processors? All of the cpuidle and cpufreq stuff
> currently works by using its own homegrown device registration methods etc, but
> surely that doesn't have to be the case?
Hmm.. So you are asking for a new cpu-driver which can be used by cpufreq and
cpuidle to get callback? If yes, where such driver will exist? And will the ACPI
processor-drivers exist parallely? Or something else?
>> > And I really feel even if we would be able to use cpu callbacks for
>> > suspend/resume, that would be a real *Hack*, because our framework doesn't want
>> > to get a callback for each of its devices (i.e. cpu) but a single callback at
>> > certain instances..
>
> Oh really? So CPUs are not individual devices any more or what?
I am not calling cpu callbacks as hack but using them for cpufreq looked like
one to me.
Replying here to the other mail as well:
On 21 November 2013 20:09, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Monday, November 18, 2013 09:37:39 PM Lan Tianyu wrote:
>> Another point, I just see cpuidle_resume() and cpuidle_pause() are
>> called in the dpm_resume_noirq and dpm_suspend_noirq(). Not sure whether
>> this can be applied to cpufreq.
>
> I don't see why not.
Interesting. So you would be happy if I add such calls after freezing userspace
and before restoring it back for cpufreq?
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