diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 0c9b44871df0..38dbafaa5341 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -993,8 +993,8 @@ enum ethtool_sfeatures_retval_bits {
 #define PORT_OTHER		0xff
 
 /* Which transceiver to use. */
-#define XCVR_INTERNAL		0x00
-#define XCVR_EXTERNAL		0x01
+#define XCVR_INTERNAL		0x00 /* PHY and MAC are in the same package */
+#define XCVR_EXTERNAL		0x01 /* PHY and MAC are in different packages */
 #define XCVR_DUMMY1		0x02
 #define XCVR_DUMMY2		0x03
 #define XCVR_DUMMY3		0x04