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Date: Tue, 28 Oct 2014 09:29:00 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Li, Aubrey" <aubrey.li@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "Brown, Len" <len.brown@intel.com>,
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Subject: Re: [RFC/PATCH] PM / Sleep: Timer quiesce in freeze state
Message-ID: <20141028082900.GP3337@twins.programming.kicks-ass.net>
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On Tue, Oct 28, 2014 at 12:32:16PM +0800, Li, Aubrey wrote:
> On 2014/10/27 15:28, Peter Zijlstra wrote:
> > On Mon, Oct 27, 2014 at 02:27:27PM +0800, Li, Aubrey wrote:
> >>> Now I suppose the problem is with cpu_pause() which needs IPIs to
> >>> complete? Do we really need cpuidle_pause() there?
> >>> cpuidle_uninstall_handlers() seems like a daft thing to call just about
> >>> there.
> >>
> >> Please check the log of 8651f97bd951d0bb1c10fa24e3fa3455193f3548.
> >> Rafael should know more this question than me.
> > 
> > That changelog explains its complete bollocks to do it here. We _want_
> > to enter and/or remain in deep idle states.
> 
> cpuidle_resume() will be called at the end of dpm_resume_noirq(). So we
> still are able to enter deep idle states after resume.

cpuidle_resume is absolute crap, as is cpuidle_suspend for that matter
-- in this case.

The only reason we needed cpuidle_suspend is because some BIOS shat its
pants when some CPUs were in higher C states while trying to do the S3
thing. We're not going to use S states or BIOS calls _at_all_, so no
point in kicking CPUs out of their deep C states.

Read that changelog you referred me to again.