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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: Mauri Carvalho <mcarvalho3@lenovo.com>
Reviewed-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Mario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
pull/1354/merge
Mario Limonciello 2025-08-27 12:17:19 -05:00 committed by Alex Deucher
parent 5e76bc677c
commit db291ed173
2 changed files with 37 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
View File

@ -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__);
aconnector->force_yuv420_output = true;
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);
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;

1
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
View File

@ -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 */