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Diffstat (limited to 'Documentation/admin-guide/pm')
| -rw-r--r-- | Documentation/admin-guide/pm/amd-pstate.rst | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 98a2bb44f80c..b6aee69f564f 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 ------------ |