drm/amdgpu/display: add dc feature mask for psr enablement

[Why]
Adding psr mask to dc features allows selectively disable/enable psr.
Current psr implementation may not work with non-pageflipping application.
Until resolved it should be disabled by default.

[How]
Add dcfeaturemask for psr enablement. Disable by default.
To enable set amdgpu.dcfeaturemask=0x8 in grub kernel command line.
Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -2424,6 +2424,7 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 		} else if (dc_link_detect(link, DETECT_REASON_BOOT)) {
 			amdgpu_dm_update_connector_after_detect(aconnector);
 			register_backlight_device(dm, link);
+			if (amdgpu_dc_feature_mask & DC_PSR_MASK)
 				amdgpu_dm_set_psr_caps(link);
 		}
 

drivers/gpu/drm/amd/include/amd_shared.h

@@ -143,6 +143,7 @@ enum PP_FEATURE_MASK {
 enum DC_FEATURE_MASK {
 	DC_FBC_MASK = 0x1,
 	DC_MULTI_MON_PP_MCLK_SWITCH_MASK = 0x2,
+	DC_PSR_MASK = 0x8,
 };
 
 enum amd_dpm_forced_level;