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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 <ray.huang@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Wyes Karny <wyes.karny@amd.com>
Tested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Perry Yuan 2023-01-31 17:00:16 +08:00 committed by Rafael J. Wysocki
parent 3ec32b6d17
commit b9e6a2d47b
1 changed files with 29 additions and 0 deletions
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Documentation/admin-guide/pm/amd-pstate.rst
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@ -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``
===============================================