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amd_pstate driver's `status` sysfs entry helps to control the driver's mode dynamically by user. After the addition of guided mode the combinations of mode transitions have been increased (16 combinations). Therefore optimise the amd_pstate_update_status function by implementing a state transition table. There are 4 states amd_pstate supports, namely: 'disable', 'passive', 'active', and 'guided'. The transition from any state to any other state is possible after this change. Sysfs interface: To disable amd_pstate driver: # echo disable > /sys/devices/system/cpu/amd_pstate/status To enable passive mode: # echo passive > /sys/devices/system/cpu/amd_pstate/status To change mode to active: # echo active > /sys/devices/system/cpu/amd_pstate/status To change mode to guided: # echo guided > /sys/devices/system/cpu/amd_pstate/status Acked-by: Huang Rui <ray.huang@amd.com> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Wyes Karny <wyes.karny@amd.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.