diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 3b08df5bcc17..09e73e061fcf 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -177,8 +177,7 @@ hardware.
 	should be terminated when another call is made with a zero
 	ctl.
 
-	Locking: none.
-	Interrupts: caller dependent.
+	Locking: caller holds port->mutex
 	This call must not sleep
 
   startup(port)