linux-kernel - Re: [PATCH v6 6/6] Documentation: amd_pstate: Update amd

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Date:   Thu, 16 Feb 2023 14:17:16 +0800
From:   Huang Rui <ray.huang@....com>
To:     "Karny, Wyes" <Wyes.Karny@....com>
Cc:     Rafael J Wysocki <rafael@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "Yuan, Perry" <Perry.Yuan@....com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        "Shukla, Santosh" <Santosh.Shukla@....com>,
        Len Brown <lenb@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        "Narayan, Ananth" <Ananth.Narayan@....com>,
        "Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
        Tor Vic <torvic9@...lbox.org>
Subject: Re: [PATCH v6 6/6] Documentation: amd_pstate: Update amd_pstate
 status sysfs for guided

On Tue, Feb 07, 2023 at 01:21:57AM +0800, Karny, Wyes wrote:
> Update amd_pstate status sysfs for guided mode.
> 
> Signed-off-by: Wyes Karny <wyes.karny@....com>
> Reviewed-by: Bagas Sanjaya <bagasdotme@...il.com>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>

Acked-by: Huang Rui <ray.huang@....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..95d2d0a803fe 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.
>  
> -- 
> 2.34.1
>