[PATCH v4 06/23] drm/connector: hdmi: Use YUV420 output format as an RGB fallback

[Cristian Ciocaltea]

Try to make use of YUV420 when computing the best output format and
RGB cannot be supported for any of the available color depths.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at collabora.com>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index 9e0a468073acbb2477eff1abef1c09d63620afaa..1fba10b92a6baa49150b6ff1e96bf2c2739bf269 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -648,14 +648,26 @@ hdmi_compute_config(const struct drm_connector *connector,
 				       8, connector->max_bpc);
 	int ret;
 
-	/*
-	 * TODO: Add support for YCbCr420 output for HDMI 2.0 capable
-	 * devices, for modes that only support YCbCr420.
-	 */
 	ret = hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc,
 				      HDMI_COLORSPACE_RGB);
+	if (!ret)
+		return 0;
 
-	return ret;
+	if (!connector->ycbcr_420_allowed) {
+		drm_dbg_kms(connector->dev,
+			    "YUV420 output format not allowed for connector.\n");
+		return -EINVAL;
+	}
+
+	ret = hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc,
+				      HDMI_COLORSPACE_YUV420);
+	if (ret) {
+		drm_dbg_kms(connector->dev,
+			    "YUV420 output format doesn't work.\n");
+		return ret;
+	}
+
+	return 0;
 }
 
 static int hdmi_generate_avi_infoframe(const struct drm_connector *connector,

-- 
2.49.0