From b9e6a2d47b2565eb450d3ee900fba49cc9b25cbd Mon Sep 17 00:00:00 2001 From: Perry Yuan Date: Tue, 31 Jan 2023 17:00:16 +0800 Subject: Documentation: amd-pstate: introduce new global sysfs attributes 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` Acked-by: Huang Rui Reviewed-by: Mario Limonciello Reviewed-by: Wyes Karny Tested-by: Wyes Karny Signed-off-by: Perry Yuan Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/amd-pstate.rst | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'Documentation/admin-guide/pm') diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index b6aee69f564f..5304adf2fc2f 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`` =============================================== -- cgit v1.2.3-58-ga151