linux-kernel - Re: 2.6.31-rc2+: Interrupts enabled after cpufreq

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Date:	Sat, 11 Jul 2009 08:23:37 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Dave Jones <davej@...hat.com>
Cc:	Marcin Slusarz <marcin.slusarz@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	cpufreq@...r.kernel.org
Subject: Re: 2.6.31-rc2+: Interrupts enabled after cpufreq_suspend

On Fri, 2009-07-10 at 15:25 -0400, Dave Jones wrote:

> The answer seems to be in 42d4dc3f4e1ec1396371aac89d0dccfdd977191b
> which introduced all this code to work around some failure that only happens
> on PPC...
> 
>     [PATCH] Add suspend method to cpufreq core
>     
>     In order to properly fix some issues with cpufreq vs. sleep on
>     PowerBooks, I had to add a suspend callback to the pmac_cpufreq driver.
>     I must force a switch to full speed before sleep and I switch back to
>     previous speed on resume.
> 
> 
> Ben, is there something better we can do here ?
> 
> I really don't want to add an #ifdef __powerpc__ to core code if we can help it.
> I'd rather we didn't call into driver guts at all from the suspend path.

Wait a minute ... having a suspend/resume method in cpufreq is one
thing, having it muck around with SMP is another :-) The ppc code
doesn't do that.

There's nothing fundamentally "fail" in requiring a switch to a given
frequency before suspend. I don't know what kind of major FAIL the K8
code is doing here though :-)

I'm happy instead of #ifdef's however to push the logic into the ppc
driver, or use a flag that the ppc driver sets to enable that logic.

Cheers,
Ben.


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