[PATCH v2 2/7] drm/connector: hdmi: Add support for YUV420 format verification

Cristian Ciocaltea
2025-03-11T10:58:02Z

Provide the necessary constraints verification in
sink_supports_format_bpc() in order to support handling of YUV420
output format.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
drivers/gpu/drm/display/drm_hdmi_state_helper.c | 40 +++++++++++++++++++++++--
1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index 6bc96d5d1ab9115989e208d9899e16cd22254fb6..e99d868edc1854eddc5ebf8692ccffb9e2338268 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -3,6 +3,7 @@
#include <drm/drm_atomic.h>
#include <drm/drm_connector.h>
#include <drm/drm_edid.h>
+#include <drm/drm_modes.h>
#include <drm/drm_print.h>

#include <drm/display/drm_hdmi_audio_helper.h>
@@ -115,6 +116,12 @@ sink_supports_format_bpc(const struct drm_connector *connector,
return false;
}

+ if (drm_mode_is_420_only(info, mode) && format != HDMI_COLORSPACE_YUV420) {
+ drm_dbg_kms(dev, "%s format unsupported by the sink for VIC%u.\n",
+ drm_hdmi_connector_get_output_format_name(format), vic);
+ return false;
+ }
+
switch (format) {
case HDMI_COLORSPACE_RGB:
drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
@@ -145,9 +152,36 @@ sink_supports_format_bpc(const struct drm_connector *connector,
return true;

case HDMI_COLORSPACE_YUV420:
- /* TODO: YUV420 is unsupported at the moment. */
- drm_dbg_kms(dev, "YUV420 format isn't supported yet.\n");
- return false;
+ drm_dbg_kms(dev, "YUV420 format, checking the constraints.\n");
+
+ if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR420)) {
+ drm_dbg_kms(dev, "Sink doesn't support YUV420.\n");
+ return false;
+ }
+
+ if (!drm_mode_is_420(info, mode)) {
+ drm_dbg_kms(dev, "Sink doesn't support YUV420 for VIC%u.\n", vic);
+ return false;
+ }
+
+ if (bpc == 10 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_30)) {
+ drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
+ return false;
+ }
+
+ if (bpc == 12 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_36)) {
+ drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
+ return false;
+ }
+
+ if (bpc == 16 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_48)) {
+ drm_dbg_kms(dev, "16 BPC but sink doesn't support Deep Color 48.\n");
+ return false;
+ }
+
+ drm_dbg_kms(dev, "YUV420 format supported in that configuration.\n");
+
+ return true;

case HDMI_COLORSPACE_YUV422:
drm_dbg_kms(dev, "YUV422 format, checking the constraints.\n");

--
2.48.1