diff --git a/include/linux/serial.h b/include/linux/serial.h
index 97ff8e2..3d86517 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -207,13 +207,15 @@
 
 struct serial_rs485 {
 	__u32	flags;			/* RS485 feature flags */
-#define SER_RS485_ENABLED		(1 << 0)
-#define SER_RS485_RTS_ON_SEND		(1 << 1)
-#define SER_RS485_RTS_AFTER_SEND	(1 << 2)
-#define SER_RS485_RTS_BEFORE_SEND	(1 << 3)
+#define SER_RS485_ENABLED		(1 << 0)	/* If enabled */
+#define SER_RS485_RTS_ON_SEND		(1 << 1)	/* Logical level for
+							   RTS pin when
+							   sending */
+#define SER_RS485_RTS_AFTER_SEND	(1 << 2)	/* Logical level for
+							   RTS pin after sent*/
 #define SER_RS485_RX_DURING_TX		(1 << 4)
-	__u32	delay_rts_before_send;	/* Milliseconds */
-	__u32	delay_rts_after_send;	/* Milliseconds */
+	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
+	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
 	__u32	padding[5];		/* Memory is cheap, new structs
 					   are a royal PITA .. */
 };