Messages in this thread Patch in this message |  | | From | Perry Yuan <> | Subject | [PATCH v9 10/13] Documentation: amd-pstate: add amd pstate driver mode introduction | Date | Mon, 26 Dec 2022 00:34:39 +0800 |
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From: Perry Yuan <Perry.Yuan@amd.com>
The amd-pstate driver has two operation modes supported: * CPPC Autonomous (active) mode * CPPC non-autonomous (passive) mode. active mode and passive mode can be chosen by different kernel parameters.
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com> --- Documentation/admin-guide/pm/amd-pstate.rst | 26 +++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 33ab8ec8fc2f..62744dae3c5f 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -299,8 +299,30 @@ module which supports the new AMD P-States mechanism on most of the future AMD platforms. The AMD P-States mechanism is the more performance and energy efficiency frequency management method on AMD processors. -Kernel Module Options for ``amd-pstate`` -========================================= + +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. + +Active Mode +------------ + +``amd_pstate=active`` + +This is the low-level firmware control mode which is implemented by ``amd_pstate_epp`` +driver with ``amd_pstate=active`` passed to the kernel in the command line. +In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software +wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. +then CPPC power algorithm will calculate the runtime workload and adjust the realtime +cores frequency according to the power supply and thermal, core voltage and some other +hardware conditions. Passive Mode ------------ -- 2.34.1
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