Re: [PATCH v10 12/12] Documentation: amd-pstate: introduce new global sysfs attributes

Huang Rui
2023-01-17T14:11:35Z

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
>