diff --git a/include/command.h b/include/command.h
index 04cd1e7..5b1577f 100644
--- a/include/command.h
+++ b/include/command.h
@@ -67,7 +67,9 @@
  *
  * @cmdtp: Command which caused the error
  * @err: Error code (0 if none, -ve for error, like -EIO)
- * @return 0 if there is not error, 1 (CMD_RET_FAILURE) if an error is found
+ * @return 0 (CMD_RET_SUCCESX) if there is not error,
+ *	   1 (CMD_RET_FAILURE) if an error is found
+ *	   -1 (CMD_RET_USAGE) if 'usage' error is found
  */
 int cmd_process_error(cmd_tbl_t *cmdtp, int err);