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

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Message-ID: <fa5e3e09eb32f5197bef2a50ced952850bf70748.camel@linux.intel.com>
Date:   Fri, 01 Mar 2019 09:39:27 -0800
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Cc:     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 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.
Can we solve this by some udev rules and offline/online cpu 1-3 on
power source change?

There are examples of changing governors on power source change.
https://bbs.archlinux.org/viewtopic.php?id=207186

Here instead of changing governor just
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 1 > /sys/devices/system/cpu/cpu1/online
echo 0 >
/sys/devices/system/cpu/cpu2/online
echo 1 >
/sys/devices/system/cpu/cpu2/online
echo 0 >
/sys/devices/system/cpu/cpu3/online
echo 1 >
/sys/devices/system/cpu/cpu3/online

Thanks,
Srinivas

> 
> Thanks,
> Rafael
>