drm/edid: convert extension block read to EDID block read helper

Use the EDID block read helper also for extension block reads, making
edid_block_read() the only place with the read retry logic.

Note: We observe that drm_do_get_edid() does not use invalid extension
blocks to flag the EDID as corrupt.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a6328b898db40235b85ad4635374bc0768b5a970.1649685475.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -2143,18 +2143,17 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 
 	for (j = 1; j <= edid->extensions; j++) {
 		void *block = edid + j;
-		int try;
 
-		for (try = 0; try < 4; try++) {
-			if (read_block(context, block, j, EDID_LENGTH))
-				goto out;
-			if (drm_edid_block_valid(block, j, false, NULL))
-				break;
-		}
+		status = edid_block_read(block, j, read_block, context);
 
-		if (try == 4)
+		edid_block_status_print(status, block, j);
+
+		if (!edid_block_status_valid(status, edid_block_tag(block))) {
+			if (status == EDID_BLOCK_READ_FAIL)
+				goto out;
 			invalid_blocks++;
 		}
+	}
 
 	if (invalid_blocks) {
 		connector_bad_edid(connector, edid, edid->extensions + 1);