Re: [RFC/PATCH] PM / Sleep: Timer quiesce in freeze state

From: "Li, Aubrey" <aubrey.li@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Brown, Len" <len.brown@intel.com>,
	"alan@linux.intel.com" <alan@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org,
	"linux-pm@vger.kernel.org >> Linux PM list" 
	<linux-pm@vger.kernel.org>
Subject: Re: [RFC/PATCH] PM / Sleep: Timer quiesce in freeze state
Date: Tue, 28 Oct 2014 15:52:17 +0800	[thread overview]
Message-ID: <544F4B31.7050308@linux.intel.com> (raw)
In-Reply-To: <20141027074419.GE10501@worktop.programming.kicks-ass.net>

On 2014/10/27 15:44, Peter Zijlstra wrote:
> On Mon, Oct 27, 2014 at 02:27:27PM +0800, Li, Aubrey wrote:
>>>> +static void freezer_suspend_tk(int cpu)
>>>>  {
>>>> +	if (tick_do_timer_cpu != cpu)
>>>> +		return;
>>>> +
>>>
>>> I had a note here that this might be broken for clocksource drivers that
>>> have suspend/resume methods. You seem to have 'lost' that note, is that
>>> because you found it isn't a problem?
>>>
>> I don't see it's a problem as long as we do not refer the clock source
>> before it resumes. But I think my testing didn't cover that case that
>> clock source drivers have suspend/resume methods. Can you please give
>> more details what do you worry about?
> 
> I can't seem to recall :/ Maybe I conflated clocksource and clockevents
> and figured we'd need to run the clocksource suspend callback on each
> cpu.

Both clocksource and clockevents are not per-cpu device, why do we need
to run their suspend callback on *each* cpu?

Thanks,
-Aubrey

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