linux-kernel - Re: [RFT][PATCH 0/2] cpufreq: intel_pstate: Handle _PPC updates on global turbo disable/enable

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Date:   Sun, 03 Mar 2019 13:20:40 -0800
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Chen Yu <yu.c.chen@...el.com>,
        Gabriele Mazzotta <gabriele.mzt@...il.com>
Subject: Re: [RFT][PATCH 0/2] cpufreq: intel_pstate: Handle _PPC updates on
 global turbo disable/enable

On Sun, 2019-03-03 at 18:03 +0100, Rafael J. Wysocki wrote:
> On Fri, Mar 1, 2019 at 6:39 PM Srinivas Pandruvada
> <srinivas.pandruvada@...ux.intel.com> wrote:
> > 
> > On Fri, 2019-03-01 at 13:43 +0100, Rafael J. Wysocki wrote:
> > > Hi All,
> > > 
> > > This is how I would fix the issue reported in BZ 200759 (see this
> > > patch series
> > > from Yu too: https://marc.info/?l=linux-pm&m=155137672924029&w=2)
> > > .
> > > 
> > > Patch [1/2] causes intel_pstate to update all policies if it gets
> > > a
> > > _PPC change
> > > notification and sees a global turbo disable/enable change.
> > > 
> > > Patch [2/2] makes it update cpuinfo.max_freq for all policies in
> > > those cases.
> > > 
> > > The patches here have not been tested yet, so testing would be
> > > much
> > > appreciated.
> > > 
> > > Of course, comments are welcome too!
> > 
> > This is the only platform, someone reported such issue.
> 
> I don't think this matters.
> 
> First, it doesn't mean that no other problems have this problem.
> 
> Second, the current handling of MSR_IA32_MISC_ENABLE_TURBO_DISABLE
> changes in intel_pstate is not sufficient if the changes is from set
> to unset anyway.
Any platform with HWP, you can't even notify of this change. So any
platform beyond SKL is not useful.
Fixing is always good :-)