linux-kernel - Re: [PATCH v4 6/6] Documentation: amd_pstate: Update amd

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Date:   Tue, 31 Jan 2023 07:12:12 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Wyes Karny <wyes.karny@....com>,
        Rafael J Wysocki <rafael@...nel.org>,
        Huang Rui <ray.huang@....com>,
        Jonathan Corbet <corbet@....net>,
        Viresh Kumar <viresh.kumar@...aro.org>, Perry.Yuan@....com
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, Bagas Sanjaya <bagasdotme@...il.com>,
        santosh.shukla@....com, Len Brown <lenb@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        Ananth Narayan <ananth.narayan@....com>,
        gautham.shenoy@....com, Tor Vic <torvic9@...lbox.org>
Subject: Re: [PATCH v4 6/6] Documentation: amd_pstate: Update amd_pstate
 status sysfs for guided

On 1/30/23 23:21, Wyes Karny wrote:
> Update amd_pstate status sysfs for guided mode.
> 
> Signed-off-by: Wyes Karny <wyes.karny@....com>
> ---
>   Documentation/admin-guide/pm/amd-pstate.rst | 31 ++++++++++++++++-----
>   1 file changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 5304adf2fc2f..56a3d11f51a5 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -303,13 +303,18 @@ efficiency frequency management method on AMD processors.
>   AMD Pstate Driver Operation Modes
>   =================================
>   
> -``amd_pstate`` CPPC has two operation modes: CPPC Autonomous(active) mode and
> -CPPC non-autonomous(passive) mode.
> -active mode and passive mode can be chosen by different kernel parameters.
> -When in Autonomous mode, CPPC ignores requests done in the Desired Performance
> -Target register and takes into account only the values set to the Minimum requested
> -performance, Maximum requested performance, and Energy Performance Preference
> -registers. When Autonomous is disabled, it only considers the Desired Performance Target.
> +``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,
> +non-autonomous (passive) mode and guided autonomous (guided) mode.
> +Active/passive/guided mode can be chosen by different kernel parameters.
> +
> +- In autonomous mode, platform ignores the desired performance level request
> +  and takes into account only the values set to the minimum, maximum and energy
> +  performance preference registers.
> +- In non-autonomous mode, platform gets desired performance level
> +  from OS directly through Desired Performance Register.
> +- In guided-autonomous mode, platform sets operating performance level
> +  autonomously according to the current workload and within the limits set by
> +  OS through min and max performance registers.
>   
>   Active Mode
>   ------------
> @@ -338,6 +343,15 @@ to the Performance Reduction Tolerance register. Above the nominal performance l
>   processor must provide at least nominal performance requested and go higher if current
>   operating conditions allow.
>   
> +Guided Mode
> +-----------
> +
> +``amd_pstate=guided``
> +
> +If ``amd_pstate=guided`` is passed to kernel command line option then this mode
> +is activated.  In this mode, driver requests minimum and maximum performance
> +level and the platform autonomously selects a performance level in this range
> +and appropriate to the current workload.
>   
>   User Space Interface in ``sysfs``
>   =================================
> @@ -358,6 +372,9 @@ control its functionality at the system level.  They are located in the
>   	"passive"
>   		The driver is functional and in the ``passive mode``
>   
> +        "guided"
> +                The driver is functional and in the ``guided mode``
> +
>   	"disable"
>   		The driver is unregistered and not functional now.
>   

Reviewed-by: Mario Limonciello <mario.limonciello@....com>