Commit db291ed1 authored by Mario Limonciello's avatar Mario Limonciello Committed by Alex Deucher
Browse files

drm/amd/display: Add fallback path for YCBCR422 



[Why]
DP validation may fail with multiple displays and higher color depths.
The sink may support others though.

[How]
When DP bandwidth validation fails, progressively fallback through:
- YUV422 8bpc (bandwidth efficient)
- YUV422 6bpc (reduced color depth)
- YUV420 (last resort)

This resolves cases where displays would show no image due to insufficient
DP link bandwidth for the requested RGB mode.

Suggested-by: default avatarMauri Carvalho <mcarvalho3@lenovo.com>
Reviewed-by: default avatarWayne Lin <wayne.lin@amd.com>
Signed-off-by: default avatarMario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: default avatarRay Wu <ray.wu@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 5e76bc67

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

+36 −9
Original line number Diff line number Diff line
@@ -6407,7 +6407,8 @@ static void fill_stream_properties_from_drm_display_mode( 
			&& aconnector->force_yuv420_output)

		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;

	else if ((connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR422)

			&& stream->signal == SIGNAL_TYPE_HDMI_TYPE_A)

			&& aconnector

			&& aconnector->force_yuv422_output)

		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR422;

	else if ((connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR444)

			&& stream->signal == SIGNAL_TYPE_HDMI_TYPE_A)
@@ -7669,6 +7670,7 @@ create_validate_stream_for_sink(struct drm_connector *connector, 
		bpc_limit = 8;



	do {

		drm_dbg_kms(connector->dev, "Trying with %d bpc\n", requested_bpc);

		stream = create_stream_for_sink(connector, drm_mode,

						dm_state, old_stream,

						requested_bpc);
@@ -7704,16 +7706,41 @@ create_validate_stream_for_sink(struct drm_connector *connector, 


	} while (stream == NULL && requested_bpc >= bpc_limit);



	if ((dc_result == DC_FAIL_ENC_VALIDATE ||

	     dc_result == DC_EXCEED_DONGLE_CAP) &&

	     !aconnector->force_yuv420_output) {

		DRM_DEBUG_KMS("%s:%d Retry forcing yuv420 encoding\n",

				     __func__, __LINE__);



	switch (dc_result) {

	/*

	 * If we failed to validate DP bandwidth stream with the requested RGB color depth,

	 * we try to fallback and configure in order:

	 * YUV422 (8bpc, 6bpc)

	 * YUV420 (8bpc, 6bpc)

	 */

	case DC_FAIL_ENC_VALIDATE:

	case DC_EXCEED_DONGLE_CAP:

	case DC_NO_DP_LINK_BANDWIDTH:

		/* recursively entered twice and already tried both YUV422 and YUV420 */

		if (aconnector->force_yuv422_output && aconnector->force_yuv420_output)

			break;

		/* first failure; try YUV422 */

		if (!aconnector->force_yuv422_output) {

			drm_dbg_kms(connector->dev, "%s:%d Validation failed with %d, retrying w/ YUV422\n",

				    __func__, __LINE__, dc_result);

			aconnector->force_yuv422_output = true;

		/* recursively entered and YUV422 failed, try YUV420 */

		} else if (!aconnector->force_yuv420_output) {

			drm_dbg_kms(connector->dev, "%s:%d Validation failed with %d, retrying w/ YUV420\n",

				    __func__, __LINE__, dc_result);

			aconnector->force_yuv420_output = true;

		}

		stream = create_validate_stream_for_sink(connector, drm_mode,

							 dm_state, old_stream);

		aconnector->force_yuv422_output = false;

		aconnector->force_yuv420_output = false;

		break;

	case DC_OK:

		break;

	default:

		drm_dbg_kms(connector->dev, "%s:%d Unhandled validation failure %d\n",

			    __func__, __LINE__, dc_result);

		break;

	}



	return stream;

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

+1 −0
Original line number Diff line number Diff line
@@ -794,6 +794,7 @@ struct amdgpu_dm_connector { 


	bool fake_enable;

	bool force_yuv420_output;

	bool force_yuv422_output;

	struct dsc_preferred_settings dsc_settings;

	union dp_downstream_port_present mst_downstream_port_present;

	/* Cached display modes */