docs: admin-guide: Add information about intel_pstate active mode

Information about intel_pstate active mode is added in the doc.
This operation mode could be used to set on the hardware when it's
not activated. Status of the mode could be checked from sysfs file
i.e., /sys/devices/system/cpu/intel_pstate/status.
The information is already available in cpu-freq/intel-pstate.txt
documentation.

Signed-off-by: Natesh Sharma <nsharma@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
[jc: reformatted for width ]
Link: https://lore.kernel.org/r/20230427083706.49882-1-nsharma@redhat.com

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685ff0534fe82714dda5e20804c38ead..430d0ef90273e1ac324d160f3f5095096184b094 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2117,6 +2117,16 @@
                        disable
                          Do not enable intel_pstate as the default
                          scaling driver for the supported processors
+                        active
+                          Use intel_pstate driver to bypass the scaling
+                          governors layer of cpufreq and provides it own
+                          algorithms for p-state selection. There are two
+                          P-state selection algorithms provided by
+                          intel_pstate in the active mode: powersave and
+                          performance.  The way they both operate depends
+                          on whether or not the hardware managed P-states
+                          (HWP) feature has been enabled in the processor
+                          and possibly on the processor model.
                        passive
                          Use intel_pstate as a scaling driver, but configure it
                          to work with generic cpufreq governors (instead of