diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 77ba0af..8395d5a 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -109,6 +109,10 @@ hardware.
 	the port does not support CTS, DCD or DSR, the driver should
 	indicate that the signal is permanently active.  If RI is
 	not available, the signal should not be indicated as active.
+	If the port does not support automatic detection of change of
+	CTS or DCD (and report via uart_handle_cts_change or 
+	uart_handle_dcd_change) the driver should indicate that the
+	signal is permanently active.
 
 	Locking: port->lock taken.
 	Interrupts: locally disabled.