[PATCH v3 0/5] AMD Pstate driver Urgent Change

Perry Yuan
2022-11-17T07:36:16Z

The patchset changed amd-pstate driver as built-in type to resolve the
driver loading sequence problem, otherwise the acpi-cpufreq driver will
be loaded as the default cpufreq scaling driver instead of amd-pstate.

Some new kernel parameters are added to allow user to disable pstate driver
and load driver with passive mode which use governors to do the
frequency scaling control.

* `amd_pstate=disabled` or no parameters will not load pstate driver.
* `amd_pstate=passive` will load pstate driver with passive mode.

Set the `amd_pstate` driver disabled by default because of performance
degradation on a number of AMD ASICs in the passive mode driver,
especially the shared memory support processors.

EPP support for the amd_pstate driver is under review. With EPP support,
the said performance issue is resolved. Once that gets upstream,
the `active` mode amd_pstate_epp driver may be enabled by default.

Changes from v2:
* pick up Acked-by flag of Huang Rui
* fix typo in the cover letter

Changes from v1:
* fix commit info in v1 patch PATCH 4/5
* pick up Reviewed-by flag of Gautham R. Shenoy
* pick up Tested-by flag of Wyes Karny

v2: https://lore.kernel.org/lkml/20221117071910.3347052-1-Perry.Yuan@amd.com/
v1: https://lore.kernel.org/lkml/20221117024955.3319484-1-Perry.Yuan@amd.com/

Perry Yuan (4):
cpufreq: amd-pstate: change amd-pstate driver to be built-in type
cpufreq: amd-pstate: add amd-pstate driver parameter for mode
selection
Documentation: amd-pstate: add driver working mode introduction
Documentation: add amd-pstate kernel command line options

Wyes Karny (1):
cpufreq: amd-pstate: cpufreq: amd-pstate: reset MSR_AMD_PERF_CTL
register at init

.../admin-guide/kernel-parameters.txt | 11 +++++
Documentation/admin-guide/pm/amd-pstate.rst | 30 +++++-------
drivers/cpufreq/Kconfig.x86 | 2 +-
drivers/cpufreq/amd-pstate.c | 49 +++++++++++++------
4 files changed, 59 insertions(+), 33 deletions(-)

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2.25.1