drm/edid: prepare for VESA vendor-specific data block extension

Current VESA vendor-specific block parsing expects real block size to be
the same as the defined struct size, use real offsets in conditionals
instead to add struct fields in future commits.

Signed-off-by: Yaroslav Bolyukin <iam@lach.pw>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

Author: CertainLach

drivers/gpu/drm/drm_edid.c

@@ -6544,7 +6544,7 @@ static void drm_parse_vesa_specific_block(struct drm_connector *connector,
 	if (oui(vesa->oui[0], vesa->oui[1], vesa->oui[2]) != VESA_IEEE_OUI)
 		return;
 
-	if (sizeof(*vesa) != sizeof(*block) + block->num_bytes) {
+	if (block->num_bytes < 5) {
 		drm_dbg_kms(connector->dev,
 			    "[CONNECTOR:%d:%s] Unexpected VESA vendor block size\n",
 			    connector->base.id, connector->name);
@@ -6567,24 +6567,22 @@ static void drm_parse_vesa_specific_block(struct drm_connector *connector,
 		break;
 	}
 
-	if (!info->mso_stream_count) {
-		info->mso_pixel_overlap = 0;
-		return;
-	}
-
-	info->mso_pixel_overlap = FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, vesa->mso);
-	if (info->mso_pixel_overlap > 8) {
+	if (info->mso_stream_count) {
+		info->mso_pixel_overlap = FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, vesa->mso);
+		if (info->mso_pixel_overlap > 8) {
+			drm_dbg_kms(connector->dev,
+				    "[CONNECTOR:%d:%s] Reserved MSO pixel overlap value %u\n",
+				    connector->base.id, connector->name,
+				    info->mso_pixel_overlap);
+			info->mso_pixel_overlap = 8;
+		}
 		drm_dbg_kms(connector->dev,
-			    "[CONNECTOR:%d:%s] Reserved MSO pixel overlap value %u\n",
+			    "[CONNECTOR:%d:%s] MSO stream count %u, pixel overlap %u\n",
 			    connector->base.id, connector->name,
-			    info->mso_pixel_overlap);
-		info->mso_pixel_overlap = 8;
+			    info->mso_stream_count, info->mso_pixel_overlap);
+	} else {
+		info->mso_pixel_overlap = 0;
 	}
-
-	drm_dbg_kms(connector->dev,
-		    "[CONNECTOR:%d:%s] MSO stream count %u, pixel overlap %u\n",
-		    connector->base.id, connector->name,
-		    info->mso_stream_count, info->mso_pixel_overlap);
 }
 
 static void drm_update_vesa_specific_block(struct drm_connector *connector,