diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d76555c..48586ac 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1219,6 +1219,8 @@
  *            The maximum supported length is 64 bytes of the input. Consider
  *            to use print_hex_dump() for the larger input.
  * - 'a' For a phys_addr_t type and its derivative types (passed by reference)
+ * - 'd[234]' For a dentry name (optionally 2-4 last components)
+ * - 'D[234]' Same as 'd' but for a struct file
  *
  * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
  * function pointers are really function descriptors, which contain a