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

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Message-ID: <1755809.pcSThauESZ@netbook>
Date:	Fri, 18 Jan 2013 21:34:29 +0100
From:	Thomas Schlichter <thomas.schlichter@....de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	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

Dear Rafael,

thank you for applying Daniel's patch. I tested 3.8-rc4 and found that one 
patch ist still missing to fix the problem of not usable C-state after 
disconnect. I had it attached with my last e-mail as patch 1. For your 
conveniency, I have attached it here again.

With that patch the problem is fixed for me. So please consider applying this, 
too.

Kind regards,
  Thomas

Am Sonntag, 13. Januar 2013, 21:04:45 schrieb Rafael J. Wysocki:
> 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
View attachment "0001-Get-power-info-before-updating-the-C-states.patch" of type "text/x-patch" (1014 bytes)