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    Subject[PATCH v8 02/13] Documentation: amd-pstate: add EPP profiles introduction
    Date
    From: Perry Yuan <Perry.Yuan@amd.com>

    The patch add AMD pstate EPP feature introduction and what EPP
    preference supported for AMD processors.

    User can get supported list from
    energy_performance_available_preferences attribute file, or update
    current profile to energy_performance_preference file

    1) See all EPP profiles
    $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_preferences
    default performance balance_performance balance_power power

    2) Check current EPP profile
    $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
    performance

    3) Set new EPP profile
    $ sudo bash -c "echo power > /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference"

    Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
    ---
    Documentation/admin-guide/pm/amd-pstate.rst | 19 +++++++++++++++++++
    1 file changed, 19 insertions(+)

    diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
    index 06e23538f79c..33ab8ec8fc2f 100644
    --- a/Documentation/admin-guide/pm/amd-pstate.rst
    +++ b/Documentation/admin-guide/pm/amd-pstate.rst
    @@ -262,6 +262,25 @@ lowest non-linear performance in `AMD CPPC Performance Capability
    <perf_cap_>`_.)
    This attribute is read-only.

    +``energy_performance_available_preferences``
    +
    +A list of all the supported EPP preferences that could be used for
    +``energy_performance_preference`` on this system.
    +These profiles represent different hints that are provided
    +to the low-level firmware about the user's desired energy vs efficiency
    +tradeoff. ``default`` represents the epp value is set by platform
    +firmware. This attribute is read-only.
    +
    +``energy_performance_preference``
    +
    +The current energy performance preference can be read from this attribute.
    +and user can change current preference according to energy or performance needs
    +Please get all support profiles list from
    +``energy_performance_available_preferences`` attribute, all the profiles are
    +integer values defined between 0 to 255 when EPP feature is enabled by platform
    +firmware, if EPP feature is disabled, driver will ignore the written value
    +This attribute is read-write.
    +
    Other performance and frequency values can be read back from
    ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.

    --
    2.34.1
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