linux-kernel - RE: [PATCH v9 02/13] Documentation: amd-pstate: add EPP profiles introduction

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Message-ID: <DM4PR12MB5278A6318FE26889D2F291FC9CFA9@DM4PR12MB5278.namprd12.prod.outlook.com>
Date:   Thu, 5 Jan 2023 03:18:23 +0000
From:   "Yuan, Perry" <Perry.Yuan@....com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "Huang, Ray" <Ray.Huang@....com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>
CC:     "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Huang, Shimmer" <Shimmer.Huang@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "Meng, Li (Jassmine)" <Li.Meng@....com>,
        "Karny, Wyes" <Wyes.Karny@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v9 02/13] Documentation: amd-pstate: add EPP profiles
 introduction

[AMD Official Use Only - General]

Hi Mario. 

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Wednesday, January 4, 2023 8:29 AM
> To: Yuan, Perry <Perry.Yuan@....com>; rafael.j.wysocki@...el.com; Huang,
> Ray <Ray.Huang@....com>; viresh.kumar@...aro.org
> Cc: Sharma, Deepak <Deepak.Sharma@....com>; Fontenot, Nathan
> <Nathan.Fontenot@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; Karny, Wyes <Wyes.Karny@....com>;
> linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v9 02/13] Documentation: amd-pstate: add EPP profiles
> introduction
> 
> On 12/25/2022 10:34, Perry Yuan wrote:
> > From: Perry Yuan <Perry.Yuan@....com>
> >
> > The amd-pstate driver supports a feature called energy performance
> > preference (EPP). Add information to the documentation to explain how
> > users can interact with the sysfs files for this feature.
> >
> > 1) See all EPP profiles
> > $ sudo cat
> >
> /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_pr
> ef
> > erences default performance balance_performance balance_power power
> >
> > 2) Check current EPP profile
> > $ sudo cat
> > /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
> > performance
> >
> > 3) Set new EPP profile
> > $ sudo bash -c "echo power >
> /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference"
> >
> > Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> 

I just got back from sick leave, will pick all your R-B flags and send v10 out. 
Thank you help to review this version.

Perry. 

> > ---
> >   Documentation/admin-guide/pm/amd-pstate.rst | 19
> +++++++++++++++++++
> >   1 file changed, 19 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/pm/amd-pstate.rst
> > b/Documentation/admin-guide/pm/amd-pstate.rst
> > index 06e23538f79c..33ab8ec8fc2f 100644
> > --- a/Documentation/admin-guide/pm/amd-pstate.rst
> > +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> > @@ -262,6 +262,25 @@ lowest non-linear performance in `AMD CPPC
> Performance Capability
> >   <perf_cap_>`_.)
> >   This attribute is read-only.
> >
> > +``energy_performance_available_preferences``
> > +
> > +A list of all the supported EPP preferences that could be used for
> > +``energy_performance_preference`` on this system.
> > +These profiles represent different hints that are provided to the
> > +low-level firmware about the user's desired energy vs efficiency
> > +tradeoff.  ``default`` represents the epp value is set by platform
> > +firmware. This attribute is read-only.
> > +
> > +``energy_performance_preference``
> > +
> > +The current energy performance preference can be read from this
> attribute.
> > +and user can change current preference according to energy or
> > +performance needs Please get all support profiles list from
> > +``energy_performance_available_preferences`` attribute, all the
> > +profiles are integer values defined between 0 to 255 when EPP feature
> > +is enabled by platform firmware, if EPP feature is disabled, driver
> > +will ignore the written value This attribute is read-write.
> > +
> >   Other performance and frequency values can be read back from
> >   ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
> >