Documentation: add amd-pstate kernel command line options

BugLink: https://bugs.launchpad.net/bugs/1998106
Add a new amd pstate driver command line option to enable driver passive
working mode via MSR and shared memory interface to request desired
performance within abstract scale and the power management firmware
(SMU) convert the perf requests into actual hardware pstates.

Also the `disable` parameter can disable the pstate driver loading by
adding `amd_pstate=disable` to kernel command line.

Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 1056d314709d0607a22e589c54b1e47e0da57b9d)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Cory Todd <cory.todd@canonical.com>
Signed-off-by: Luke Nowakowski-Krijger <luke.nowakowskikrijger@canonical.com>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bfc1f87aa9aeabdb603dffdc075e944ae70974ec..b5272568a8f35dc7759169e39bd13955df09b802 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6536,3 +6536,14 @@
                                memory, and other data can't be written using
                                xmon commands.
                        off     xmon is disabled.
+
+       amd_pstate=     [X86]
+                       disable
+                         Do not enable amd_pstate as the default
+                         scaling driver for the supported processors
+                       passive
+                         Use amd_pstate as a scaling driver, driver requests a
+                         desired performance on this abstract scale and the power
+                         management firmware translates the requests into actual
+                         hardware states (core frequency, data fabric and memory
+                         clocks etc.)