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From:   Perry Yuan <Perry.Yuan@amd.com>
To:     <rafael.j.wysocki@intel.com>, <ray.huang@amd.com>,
        <viresh.kumar@linaro.org>
CC:     <Deepak.Sharma@amd.com>, <Mario.Limonciello@amd.com>,
        <Nathan.Fontenot@amd.com>, <Alexander.Deucher@amd.com>,
        <Shimmer.Huang@amd.com>, <Xiaojian.Du@amd.com>, <Li.Meng@amd.com>,
        <linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Perry Yuan <Perry.Yuan@amd.com>
Subject: [PATCH v3 2/8] Documentation: amd-pstate: add EPP profiles introduction
Date:   Tue, 8 Nov 2022 01:56:59 +0800
Message-ID: <20221107175705.2207842-3-Perry.Yuan@amd.com>
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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 8f3d30c5a0d8..78c6525d5a49 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``
+
+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