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Documentation: cpufreq: amd-pstate: Update amd_pstate status sysfs for guided

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Update amd_pstate status sysfs for guided mode.

Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.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>
This commit is contained in:
Wyes Karny 2023-03-07 11:27:40 +00:00 committed by Rafael J. Wysocki
parent 3ca7bc818d
commit 7a9dec665f
1 changed files with 24 additions and 7 deletions
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31
Documentation/admin-guide/pm/amd-pstate.rst
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@ -303,13 +303,18 @@ efficiency frequency management method on AMD processors.
AMD Pstate Driver Operation Modes
=================================
``amd_pstate`` CPPC has two operation modes: CPPC Autonomous(active) mode and
CPPC non-autonomous(passive) mode.
active mode and passive mode can be chosen by different kernel parameters.
When in Autonomous mode, CPPC ignores requests done in the Desired Performance
Target register and takes into account only the values set to the Minimum requested
performance, Maximum requested performance, and Energy Performance Preference
registers. When Autonomous is disabled, it only considers the Desired Performance Target.
``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,
non-autonomous (passive) mode and guided autonomous (guided) mode.
Active/passive/guided mode can be chosen by different kernel parameters.
- In autonomous mode, platform ignores the desired performance level request
and takes into account only the values set to the minimum, maximum and energy
performance preference registers.
- In non-autonomous mode, platform gets desired performance level
from OS directly through Desired Performance Register.
- In guided-autonomous mode, platform sets operating performance level
autonomously according to the current workload and within the limits set by
OS through min and max performance registers.
Active Mode
------------
@ -338,6 +343,15 @@ to the Performance Reduction Tolerance register. Above the nominal performance l
processor must provide at least nominal performance requested and go higher if current
operating conditions allow.
Guided Mode
-----------
``amd_pstate=guided``
If ``amd_pstate=guided`` is passed to kernel command line option then this mode
is activated. In this mode, driver requests minimum and maximum performance
level and the platform autonomously selects a performance level in this range
and appropriate to the current workload.
User Space Interface in ``sysfs`` - General
===========================================
@ -358,6 +372,9 @@ control its functionality at the system level. They are located in the
"passive"
The driver is functional and in the ``passive mode``
"guided"
The driver is functional and in the ``guided mode``
"disable"
The driver is unregistered and not functional now.