[RFC 17/19] drm/edid: detect color formats and CEA revision only on CEA extension

[Jani Nikula]

The CTA data block in DisplayID does not have the bits from byte 3 that
a CEA extension has. Only look for them in CEA extensions, but also look
for them in all CEA extensions.

The DisplayID CTA data block version does not seem to match the CEA
revision either. Ignore it for the purpose of CEA revision.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/drm_edid.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index b6675f8638bb..f40427dc5236 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -5293,22 +5293,31 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 			      const struct edid *edid)
 {
 	struct drm_display_info *info = &connector->display_info;
+	struct drm_edid_iter edid_iter;
 	const struct cea_db *db;
 	struct cea_db_iter iter;
-	const u8 *edid_ext;
+	const u8 *cea;
 
-	edid_ext = drm_find_cea_extension(edid);
-	if (!edid_ext)
-		return;
+	drm_edid_iter_begin(edid, &edid_iter);
+	drm_edid_iter_for_each(cea, &edid_iter) {
+		if (cea[0] != CEA_EXT)
+			continue;
 
-	info->cea_rev = edid_ext[1];
+		if (!info->cea_rev)
+			info->cea_rev = cea[1];
 
-	/* The existence of a CEA block should imply RGB support */
-	info->color_formats = DRM_COLOR_FORMAT_RGB444;
-	if (edid_ext[3] & EDID_CEA_YCRCB444)
-		info->color_formats |= DRM_COLOR_FORMAT_YCBCR444;
-	if (edid_ext[3] & EDID_CEA_YCRCB422)
-		info->color_formats |= DRM_COLOR_FORMAT_YCBCR422;
+		if (info->cea_rev != cea[1])
+			DRM_DEBUG_KMS("CEA extension version mismatch %u != %u\n",
+				      info->cea_rev, cea[1]);
+
+		/* The existence of a CEA block should imply RGB support */
+		info->color_formats = DRM_COLOR_FORMAT_RGB444;
+		if (cea[3] & EDID_CEA_YCRCB444)
+			info->color_formats |= DRM_COLOR_FORMAT_YCBCR444;
+		if (cea[3] & EDID_CEA_YCRCB422)
+			info->color_formats |= DRM_COLOR_FORMAT_YCBCR422;
+	}
+	drm_edid_iter_end(&edid_iter);
 
 	cea_db_iter_edid_begin(edid, &iter);
 	cea_db_iter_for_each(db, &iter) {
-- 
2.30.2