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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2026-07-31 19:36:04 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2026-07-31 19:36:04 +0200
commiteb49643e66e0dd0b989e30a1c556e8c5d5398dc0 (patch)
tree86d7e8dfebd3873b8cdc771692a6fe5400b6e5fa /Documentation/admin-guide/pm
parent9e4cb21f2940230efc09f90c8335b5cbb3e26c41 (diff)
parentd06c75c22d5c95ee27e01fedcaa07231c9bd5c88 (diff)
Merge tag 'amd-pstate-v7.3-2026-07-30' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux
Pull amd-pstate 7.3 content (07/30/26) from Mario Limonciello: "* Changes for dynamic EPP * Adjustments to the bios min perf feature * Fixes to kernel doc" * tag 'amd-pstate-v7.3-2026-07-30' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux: cpufreq/amd-pstate: Document missing kernel-doc members cpufreq/amd-pstate-ut: Add unit test for CPPC Performance Priority cpufreq/amd-pstate-ut: Add unit test for "dynamic" EPP mode cpufreq/amd-pstate: Reduce the scope of exported symbols Documentation/amd-pstate: Update dynamic_epp documentation with new behavior cpufreq/amd-pstate: Remove "amd_dynamic_epp" cmdline and "dynamic_epp" sysfs cpufreq/amd-pstate: Add dynamic EPP as an "energy_performance_preference" mode cpufreq/amd-pstate: Extract platform profile to EPP conversion into a helper cpufreq/amd-pstate: Remove the defensive check for bios_min_perf cpufreq/amd-pstate: Set min_limit_freq based on bios_min_perf
Diffstat (limited to 'Documentation/admin-guide/pm')
-rw-r--r--Documentation/admin-guide/pm/amd-pstate.rst45
1 files changed, 22 insertions, 23 deletions
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index a95e2ebce005..c7bf7cc2db87 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -317,7 +317,9 @@ 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. ``custom`` designates that integer values 0-255 may be written
-as well. This attribute is read-only.
+as well. ``dynamic`` designates that the EPP is modified dynamically
+on kernel events. See ``Dynamic energy performance profile`` section below to
+know more about the ``dynamic`` mode. This attribute is read-only.
``energy_performance_preference``
@@ -326,13 +328,11 @@ and user can change current preference according to energy or performance needs
Coarse named profiles are available in the attribute
``energy_performance_available_preferences``.
Users can also write individual integer values between 0 to 255.
-When dynamic EPP is enabled, writes to energy_performance_preference are blocked
-even when EPP feature is enabled by platform firmware. Lower epp values shift the bias
-towards improved performance while a higher epp value shifts the bias towards
-power-savings. The exact impact can change from one platform to the other.
-If a valid integer was last written, then a number will be returned on future reads.
-If a valid string was last written then a string will be returned on future reads.
-This attribute is read-write.
+Lower epp values shift the bias towards improved performance while a higher epp
+value shifts the bias towards power-savings. The exact impact can change from
+one platform to the other. If a valid integer was last written, then a number
+will be returned on future reads. If a valid string was last written then a
+string will be returned on future reads. This attribute is read-write.
``boost``
The `boost` sysfs attribute provides control over the CPU core
@@ -356,21 +356,20 @@ Other performance and frequency values can be read back from
Dynamic energy performance profile
==================================
The amd-pstate driver supports dynamically selecting the energy performance
-profile based on whether the machine is running on AC or DC power.
-
-Whether this behavior is enabled by default depends on the kernel command line option
-``amd_dynamic_epp`` is set. This behavior can also be overridden
-at runtime by the sysfs file ``/sys/devices/system/cpu/amd_pstate/dynamic_epp``.
-
-When set to enabled, the driver will select a different energy performance
-profile when the machine is running on battery or AC power. The driver will
-also register with the platform profile handler to receive notifications of
-user desired power state and react to those.
-When set to disabled, the driver will not change the energy performance profile
-based on the power source and will not react to user desired power state.
-
-Attempting to manually write to the ``energy_performance_preference`` sysfs
-file will fail when ``dynamic_epp`` is enabled.
+profile based on the system profile and the current power source in active mode.
+
+The ``dynamic`` mode is listed in
+``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_available_preferences``
+when available while running under the ``powersave`` governor. The ``dynamic``
+mode can be toggled on by writing the same to the sysfs file
+``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_preference`` when
+available.
+
+When ``energy_performance_preference`` is set to ``dynamic``, the driver will
+select a different energy performance profile when the machine is running on
+battery or AC power. The driver will also register with the platform profile
+handler to receive notifications of user desired power state and react to
+those.
``amd-pstate`` vs ``acpi-cpufreq``
======================================