linux-kernel - Re: [PATCH] cpuidle: fix new C-states not functional after AC disconnect

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Date:	Sun, 13 Jan 2013 21:04:45 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:	Thomas Schlichter <thomas.schlichter@....de>,
	Len Brown <lenb@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	Andreas Müller <goo@...pelspeicher.org>,
	Julius Werner <jwerner@...omium.org>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpuidle: fix new C-states not functional after AC disconnect

On Sunday, January 13, 2013 03:41:34 PM Daniel Lezcano wrote:
> On 01/13/2013 01:34 PM, Thomas Schlichter wrote:
> > Hi,
> > 
> > there is a long-standing regression about new C-states not working after 
> > disconnecting AC power from a laptop if the cpuidle driver "acpi-idle" is 
> > used. It was reported here:
> > 
> > [1] https://bugzilla.kernel.org/show_bug.cgi?id=42870  (March 5th 2012)
> > [2] https://bugzilla.kernel.org/show_bug.cgi?id=43349  (June 7th 2012)
> > [3] https://lkml.org/lkml/2012/10/16/518   (October 19th 2012)
> > 
> > In [1] Andreas proposed a patch that initialized the missing power_usage 
> > values from within acpi_idle in the same way as cpuidle does.
> > In [2] I proposed a patch to use the power values provided by ACPI to 
> > initialize the power_usage variables.
> > In [3] Julius proposed a patch to call the initialization function 
> > set_power_states()  not only once, but always when the C-states change.
> > 
> > Currently, Daniel Lezcano seems to be working on an intrusive change of not 
> > using the power_usage value at all for choosing a C-state:
> > 
> > [4] https://lkml.org/lkml/2012/12/14/155
> > 
> > As I could not find any of these patches in any git trees to be merged for 
> > 3.8, I propose an other, least intrusive patch for the time being. It is 
> > attached an initializes _all_ power_usage values in the first place.
> > 
> > As this is a real power consumption regression since 3.2, I really ask you to 
> > apply anything and push it to stable, too!
> 
> Rafael, is possible to apply the patch [1/2] I previously sent ?
> 
> https://patchwork.kernel.org/patch/1878691/

I need to talk about this with Len.  That should happen tomorrow if everything
goes well.

> So we get this bug fixed.
> 
> I will resend the patch [2/2] as soon as possible.

OK

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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