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Date: Tue, 11 Oct 2022 00:22:44 +0800 From: Perry Yuan <Perry.Yuan@....com> To: <rafael.j.wysocki@...el.com>, <ray.huang@....com>, <viresh.kumar@...aro.org> CC: <Deepak.Sharma@....com>, <Mario.Limonciello@....com>, <Nathan.Fontenot@....com>, <Alexander.Deucher@....com>, <Shimmer.Huang@....com>, <Xiaojian.Du@....com>, <Li.Meng@....com>, <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Perry Yuan <Perry.Yuan@....com> Subject: [RESEND PATCH V2 5/9] Documentation: amd-pstate: add EPP profiles introduction 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@....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 83b58eb4ab4d..d0f0e115013b 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -261,6 +261,25 @@ lowest non-linear performance in `AMD CPPC Performance Capability <perf_cap_>`_.) This attribute is read-only. +``energy_performance_available_preferences`` + +All the supported EPP preference could be selected, List of the strings that +can be set to the ``energy_performance_preference`` attribute +those different profiles represent different energy vs efficiency hints provided +to low-level firmware +however, the ``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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