linux-kernel - Re: [PATCH 1/8] cpufreq: Revert commit a66b2e to fix cpufreq regression during suspend/resume

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Date:	Sat, 13 Jul 2013 14:46:25 +0200
From:	Paul Bolle <pebolle@...cali.nl>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>, rjw@...k.pl,
	toralf.foerster@....de, robert.jarzmik@...el.com,
	durgadoss.r@...el.com, tianyu.lan@...el.com,
	lantianyu1986@...il.com, dirk.brandewie@...il.com,
	stern@...land.harvard.edu, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/8] cpufreq: Revert commit a66b2e to fix cpufreq
 regression during suspend/resume

On Fri, 2013-07-12 at 12:48 +0530, Viresh Kumar wrote:
> On 12 July 2013 03:45, Srivatsa S. Bhat
> <srivatsa.bhat@...ux.vnet.ibm.com> wrote:
> > commit a66b2e (cpufreq: Preserve sysfs files across suspend/resume) has
> > unfortunately caused several things in the cpufreq subsystem to break subtly
> > after a suspend/resume cycle.
> >
> > The intention of that patch was to retain the file permissions of the
> > cpufreq related sysfs files across suspend/resume. To achieve that, the commit
> > completely removed the calls to cpufreq_add_dev() and __cpufreq_remove_dev()
> > during suspend/resume transitions. But the problem is that those functions
> > do 2 kinds of things:
> >   1. Low-level initialization/tear-down that are critical to the correct
> >      functioning of cpufreq-core.
> >   2. Kobject and sysfs related initialization/teardown.
> >
> > Ideally we should have reorganized the code to cleanly separate these two
> > responsibilities, and skipped only the sysfs related parts during
> > suspend/resume. Since we skipped the entire callbacks instead (which also
> > included some CPU and cpufreq-specific critical components), cpufreq
> > subsystem started behaving erratically after suspend/resume.
> >
> > So revert the commit to fix the regression. We'll revisit and address the
> > original goal of that commit separately, since it involves quite a bit of
> > careful code reorganization and appears to be non-trivial.
> >
> > (While reverting the commit, note that another commit f51e1eb "cpufreq:
> > Fix cpufreq regression after suspend/resume" already reverted part of the
> > original set of changes. So revert only the remaining ones).
> >
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> > ---
> >
> >  drivers/cpufreq/cpufreq.c       |    4 +++-
> >  drivers/cpufreq/cpufreq_stats.c |    6 ++----
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

This seems to fix the "core stuck at some frequency after resume" issue
I ran into since v3.10. So:

Tested-by: Paul Bolle <pebolle@...cali.nl>


Paul Bolle

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