Subject: [PATCH v15 08/28] drm/display: hdmi-state-helper: Act on color format DRM property

From: Nicolas Frattaroli <[email-masked]>
Date: Fri, 22 May 2026 14:31:59 +0200

With the introduction of the "color format" DRM property, which allows
userspace to request a specific color format, the HDMI state helper
should implement this.

Implement it by translating the requested drm_connector_color_format to
a drm_output_color_format enum value as per the logic HDMI should use
for this: Auto is translated to RGB, and a fallback to YUV420 is only
performed if the original color format was auto.

Reviewed-by: Dmitry Baryshkov <[email-masked]>
Reviewed-by: Maxime Ripard <[email-masked]>
Reviewed-by: Daniel Stone <[email-masked]>
Signed-off-by: Nicolas Frattaroli <[email-masked]>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c | 31 +++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index 3ba47564caad..1c54e6feac61 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -670,8 +670,39 @@ hdmi_compute_config(const struct drm_connector *connector,
 	unsigned int max_bpc = clamp_t(unsigned int,
 				       conn_state->max_bpc,
 				       8, connector->max_bpc);
+	enum drm_output_color_format fmt;
 	int ret;
 
+	if (conn_state->color_format != DRM_CONNECTOR_COLOR_FORMAT_AUTO) {
+		switch (conn_state->color_format) {
+		case DRM_CONNECTOR_COLOR_FORMAT_AUTO:
+			drm_warn(connector->dev, "AUTO format in non-AUTO path.\n");
+			fallthrough;
+		case DRM_CONNECTOR_COLOR_FORMAT_RGB444:
+			fmt = DRM_OUTPUT_COLOR_FORMAT_RGB444;
+			break;
+		case DRM_CONNECTOR_COLOR_FORMAT_YCBCR444:
+			fmt = DRM_OUTPUT_COLOR_FORMAT_YCBCR444;
+			break;
+		case DRM_CONNECTOR_COLOR_FORMAT_YCBCR422:
+			fmt = DRM_OUTPUT_COLOR_FORMAT_YCBCR422;
+			break;
+		case DRM_CONNECTOR_COLOR_FORMAT_YCBCR420:
+			fmt = DRM_OUTPUT_COLOR_FORMAT_YCBCR420;
+			break;
+		default:
+			drm_dbg_kms(connector->dev, "HDMI does not support color format '%d'.\n",
+				conn_state->color_format);
+			return -EINVAL;
+		}
+
+		return hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc, fmt);
+	}
+
+	/*
+	 * For %DRM_CONNECTOR_COLOR_FORMAT_AUTO, try RGB first, and fall back
+	 * to the less bandwidth-intensive YCBCR420 if RGB fails.
+	 */
 	ret = hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc,
 				      DRM_OUTPUT_COLOR_FORMAT_RGB444);
 	if (ret) {

-- 
2.54.0