drm/amd/display: Enable PSR by default on newer DCN

[Why]
For optimal power savings on panels that can support it.

This was previously left disabled by default because of issues with
compositors that do not pageflip and scan out directly to the
frontbuffer.

For these compositors we now have detection methods that wait for x
number of pageflips after a full update - triggered by a buffer or
format change typically.

This may introduce bugs or new cases not tested by users so this is
only currently targeting newer DCN.

[How]
Add code in DM to set PSR state by default for newer DCN while falling
back to the feature mask for older.

Add a global debug flag that can be set to disable it for either.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4031,6 +4031,7 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 	int32_t primary_planes;
 	enum dc_connection_type new_connection_type = dc_connection_none;
 	const struct dc_plane_cap *plane;
+	bool psr_feature_enabled = false;
 
 	dm->display_indexes_num = dm->dc->caps.max_streams;
 	/* Update the actual used number of crtc */
@@ -4113,6 +4114,19 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 		DRM_DEBUG_KMS("Unsupported DCN IP version for outbox: 0x%X\n",
 			      adev->ip_versions[DCE_HWIP][0]);
 	}
+
+	/* Determine whether to enable PSR support by default. */
+	if (!(amdgpu_dc_debug_mask & DC_DISABLE_PSR)) {
+		switch (adev->ip_versions[DCE_HWIP][0]) {
+		case IP_VERSION(3, 1, 2):
+		case IP_VERSION(3, 1, 3):
+			psr_feature_enabled = true;
+			break;
+		default:
+			psr_feature_enabled = amdgpu_dc_feature_mask & DC_PSR_MASK;
+			break;
+		}
+	}
 #endif
 
 	/* loops over all connectors on the board */
@@ -4156,7 +4170,8 @@ 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)
+
+			if (psr_feature_enabled)
 				amdgpu_dm_set_psr_caps(link);
 		}
 

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

@@ -228,7 +228,7 @@ enum DC_FEATURE_MASK {
 	DC_FBC_MASK = (1 << 0), //0x1, disabled by default
 	DC_MULTI_MON_PP_MCLK_SWITCH_MASK = (1 << 1), //0x2, enabled by default
 	DC_DISABLE_FRACTIONAL_PWM_MASK = (1 << 2), //0x4, disabled by default
-	DC_PSR_MASK = (1 << 3), //0x8, disabled by default
+	DC_PSR_MASK = (1 << 3), //0x8, disabled by default for dcn < 3.1
 	DC_EDP_NO_POWER_SEQUENCING = (1 << 4), //0x10, disabled by default
 };
 
@@ -236,7 +236,8 @@ enum DC_DEBUG_MASK {
 	DC_DISABLE_PIPE_SPLIT = 0x1,
 	DC_DISABLE_STUTTER = 0x2,
 	DC_DISABLE_DSC = 0x4,
-	DC_DISABLE_CLOCK_GATING = 0x8
+	DC_DISABLE_CLOCK_GATING = 0x8,
+	DC_DISABLE_PSR = 0x10,
 };
 
 enum amd_dpm_forced_level;