[PATCH v2] Add PP_FEATURE_MASK comments

[Ryan Taylor]

Documents PP_FEATURE_MASK enum.
Provides instructions on how to use ppfeaturemasks.

v2: Improved enum definitions. Adds kernel command line
    parameters to ppfeaturemask instructions.

Signed-off-by: Ryan Taylor <ryan.taylor at amd.com>
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/include/amd_shared.h | 28 ++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h
index e98c84ef206f..7c84d5beb600 100644
--- a/drivers/gpu/drm/amd/include/amd_shared.h
+++ b/drivers/gpu/drm/amd/include/amd_shared.h
@@ -128,6 +128,34 @@ enum amd_powergating_state {
 #define AMD_PG_SUPPORT_ATHUB			(1 << 16)
 #define AMD_PG_SUPPORT_JPEG			(1 << 17)
 
+/**
+* enum PP_FEATURE_MASK - Used to mask power play features.
+*
+* @PP_SCLK_DPM_MASK: Dynamic adjustment of the system (graphics) clock.
+* @PP_MCLK_DPM_MASK: Dynamic adjustment of the memory clock.
+* @PP_PCIE_DPM_MASK: Dynamic adjustment of PCIE clocks and lanes.
+* @PP_SCLK_DEEP_SLEEP_MASK: System (graphics) clock deep sleep.
+* @PP_POWER_CONTAINMENT_MASK: Power containment.
+* @PP_UVD_HANDSHAKE_MASK: Unified video decoder handshake.
+* @PP_SMC_VOLTAGE_CONTROL_MASK: Dynamic voltage control.
+* @PP_VBI_TIME_SUPPORT_MASK: Vertical blank interval support.
+* @PP_ULV_MASK: Ultra low voltage.
+* @PP_ENABLE_GFX_CG_THRU_SMU: SMU control of GFX engine clockgating.
+* @PP_CLOCK_STRETCH_MASK: Clock stretching.
+* @PP_OD_FUZZY_FAN_CONTROL_MASK: Overdrive fuzzy fan control.
+* @PP_SOCCLK_DPM_MASK: Dynamic adjustment of the SoC clock.
+* @PP_DCEFCLK_DPM_MASK: Dynamic adjustment of the Display Controller Engine Fabric clock.
+* @PP_OVERDRIVE_MASK: Over- and under-clocking support.
+* @PP_GFXOFF_MASK: Dynamic graphics engine power control.
+* @PP_ACG_MASK: Adaptive clock generator.
+* @PP_STUTTER_MODE: Stutter mode.
+* @PP_AVFS_MASK: Adaptive voltage and frequency scaling.
+*
+* To override these settings on boot, append amdgpu.ppfeaturemask=<mask> to
+* the kernel's command line parameters. This is usually done through a system's
+* boot loader (E.g. GRUB). If manually loading the driver, pass
+* ppfeaturemask=<mask> as a modprobe parameter.
+*/
 enum PP_FEATURE_MASK {
 	PP_SCLK_DPM_MASK = 0x1,
 	PP_MCLK_DPM_MASK = 0x2,
-- 
2.28.0