linux-kernel - RE: [PATCH v9 13/13] Documentation: amd-pstate: introduce new global sysfs attributes

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Date:   Thu, 5 Jan 2023 06:21:13 +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 13/13] Documentation: amd-pstate: introduce new global
 sysfs attributes

[AMD Official Use Only - General]

Hi Mario. 

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Wednesday, January 4, 2023 8:35 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 13/13] Documentation: amd-pstate: introduce new
> global sysfs attributes
> 
> On 12/25/2022 10:34, Perry Yuan wrote:
> > The amd-pstate driver supports switching working modes at runtime.
> > Users can view and change modes by interacting with the "status" sysfs
> > attribute.
> >
> > 1) check driver mode:
> > $ cat /sys/devices/system/cpu/amd-pstate/status
> >
> > 2) switch mode:
> > `# echo "passive" | sudo tee
> > /sys/devices/system/cpu/amd-pstate/status`
> > or
> > `# echo "active" | sudo tee /sys/devices/system/cpu/amd-pstate/status`
> >
> > Signed-off-by: Perry Yuan <perry.yuan@....com>
> > ---
> >   Documentation/admin-guide/pm/amd-pstate.rst | 29
> +++++++++++++++++++++
> >   1 file changed, 29 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/pm/amd-pstate.rst
> > b/Documentation/admin-guide/pm/amd-pstate.rst
> > index 62744dae3c5f..5f6379475b32 100644
> > --- a/Documentation/admin-guide/pm/amd-pstate.rst
> > +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> > @@ -339,6 +339,35 @@ processor must provide at least nominal
> performance requested and go higher if c
> >   operating conditions allow.
> >
> >
> > +User Space Interface in ``sysfs``
> > +=================================
> > +
> > +Global Attributes
> > +-----------------
> > +
> > +``amd-pstate`` exposes several global attributes (files) in ``sysfs``
> > +to control its functionality at the system level.  They are located
> > +in the ``/sys/devices/system/cpu/amd-pstate/`` directory and affect all
> CPUs.
> > +
> > +``status``
> > +	Operation mode of the driver: "active", "passive" or "disable".
> > +
> > +	"active"
> > +		The driver is functional and in the ``active mode``
> > +
> > +	"passive"
> > +		The driver is functional and in the ``passive mode``
> > +
> > +	"disable"
> > +		The driver is unregistered and not functional now.
> > +
> > +        This attribute can be written to in order to change the driver's
> > +        operation mode or to unregister it.  The string written to it must be
> > +        one of the possible values of it and, if successful, writing one of
> > +        these values to the sysfs file will cause the driver to cause
> > + the driver
> 
> "will cause the driver to cause the driver to"?
> 
> Presumably you mean just "will cause the driver to"
> 
> With that fixed:
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>

Thanks for the review, will fix the words and pick up the RB tag in v10. 

Perry.

> 
> > +        to switch over to the operation mode represented by that string - or
> to be
> > +        unregistered in the "disable" case.
> > +
> >   ``cpupower`` tool support for ``amd-pstate``
> >   ===============================================
> >