diff --git a/Documentation/pnp.txt b/Documentation/pnp.txt
index af0f6ea..9529c9c 100644
--- a/Documentation/pnp.txt
+++ b/Documentation/pnp.txt
@@ -115,6 +115,9 @@
 pnp_register_driver
 - adds a PnP driver to the Plug and Play Layer
 - this includes driver model integration
+- returns zero for success or a negative error number for failure; count
+  calls to the .add() method if you need to know how many devices bind to
+  the driver
 
 pnp_unregister_driver
 - removes a PnP driver from the Plug and Play Layer