From mboxrd@z Thu Jan  1 00:00:00 1970
From: rosslagerwall@gmail.com
Subject: Re: [stable request <=3.7] acpi-cpufreq: set current frequency based
 on target P-State
Date: Wed, 26 Mar 2014 07:22:32 +0000
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To: Vinson Lee <vlee@twopensource.com>
Cc: stable@vger.kernel.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Viresh Kumar <viresh.kumar@linaro.org>, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, Len Brown <len.brown@intel.com>, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>, Shatil Rafiullah <srafiullah@twopensource.com>

On Tue, Mar 25, 2014 at 03:53:40PM -0700, Vinson Lee wrote:
> On Tue, Mar 25, 2014 at 3:18 PM,  <rosslagerwall@gmail.com> wrote:
> > On Tue, Mar 25, 2014 at 03:04:16PM -0700, Vinson Lee wrote:
> >> Hi.
> >>
> >> Please backport upstream commit 8673b83bf2f013379453b4779047bf3c6ae387e4
> >> "acpi-cpufreq: set current frequency based on target P-State" to stable
> >> kernels 3.7 and earlier. This patch enables the kernel to control
> >> P-states on several platforms. Without this patch, the kernel was unable
> >> to control P-states on the same platforms.
> >>
> >> The upstream patch cleanly applies to 3.7.
> >>
> >> A backported patch is needed with the removal of SYSTEM_AMD_MSR_CAPABLE
> >> for kernels 3.6 and earlier.
> >>
> >
> > I seem to recall that the problem was a regression introduced by commit
> > 5a1c0228 (cpufreq: Avoid calling cpufreq driver's target() routine if
> > target_freq == policy->cur) which was introduced in the 3.8 cycle.  Are
> > you sure it is necessary for kernels < 3.8?
> >
> > Regards
> > --
> > Ross Lagerwall
> 
> 
> This specific patch allows P-states to work with the 3.4 kernel on
> several hardware platforms.
> 
> Perhaps this is not the correct patch to backport. However, P-states
> are not working properly with the 3.4 kernel, even though it does not
> have the regression commit 5a1c0228 "cpufreq: Avoid calling cpufreq
> driver's target() routine if target_freq == policy->cur" backported.
> 

Fair enough,

Cheers
-- 
Ross Lagerwall