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Date:   Tue, 17 Jan 2023 22:11:00 +0800
From:   Huang Rui <ray.huang@amd.com>
To:     "Yuan, Perry" <Perry.Yuan@amd.com>
Cc:     "rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        "viresh.kumar@linaro.org" <viresh.kumar@linaro.org>,
        "Sharma, Deepak" <Deepak.Sharma@amd.com>,
        "Fontenot, Nathan" <Nathan.Fontenot@amd.com>,
        "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "Huang, Shimmer" <Shimmer.Huang@amd.com>,
        "Du, Xiaojian" <Xiaojian.Du@amd.com>,
        "Meng, Li (Jassmine)" <Li.Meng@amd.com>,
        "Karny, Wyes" <Wyes.Karny@amd.com>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
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Subject: Re: [PATCH v10 12/12] Documentation: amd-pstate: introduce new
 global sysfs attributes
Message-ID: <Y8asdDS6EZl+dwvi@amd.com>
References: <20230106061420.95715-1-perry.yuan@amd.com>
 <20230106061420.95715-13-perry.yuan@amd.com>
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On Fri, Jan 06, 2023 at 02:14:20PM +0800, Yuan, Perry 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`
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>

Patch 9, 10, and 12 are Acked-by: Huang Rui <ray.huang@amd.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..df0637a49f47 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 switch over
> +        to the operation mode represented by that string - or to be
> +        unregistered in the "disable" case.
> +
>  ``cpupower`` tool support for ``amd-pstate``
>  ===============================================
>  
> -- 
> 2.34.1
>