diff -r ffd9aeb1e7ef sys/dev/re/if_re.c
--- a/sys/dev/re/if_re.c	Mon May 07 23:58:27 2012 +0200
+++ b/sys/dev/re/if_re.c	Tue Jan 15 01:10:46 2013 +0100
@@ -174,6 +174,8 @@
 static const struct rl_type const re_devs[] = {
 	{ DLINK_VENDORID, DLINK_DEVICEID_528T, 0,
 	    "D-Link DGE-528(T) Gigabit Ethernet Adapter" },
+	{ DLINK_VENDORID, DLINK_DEVICEID_520TX, 0,
+	    "D-Link DFE-520(TX) Gigabit Ethernet Adapter" },
 	{ DLINK_VENDORID, DLINK_DEVICEID_530T_REVC, 0,
 	    "D-Link DGE-530(T) Gigabit Ethernet Adapter" },
 	{ RT_VENDORID, RT_DEVICEID_8139, 0,
@@ -1214,7 +1216,7 @@
 	 * Because RTL8169SC does not seem to work when memory mapping
 	 * is used always activate io mapping.
 	 */
-	if (devid == RT_DEVICEID_8169SC)
+	if (devid == RT_DEVICEID_8169SC || devid == DLINK_DEVICEID_520TX)
 		prefer_iomap = 1;
 	if (prefer_iomap == 0) {
 		sc->rl_res_id = PCIR_BAR(1);
diff -r ffd9aeb1e7ef sys/pci/if_rlreg.h
--- a/sys/pci/if_rlreg.h	Mon May 07 23:58:27 2012 +0200
+++ b/sys/pci/if_rlreg.h	Tue Jan 15 01:10:46 2013 +0100
@@ -1048,6 +1048,11 @@
 #define	DLINK_DEVICEID_530TXPLUS		0x1300
 
 /*
+ * D-Link DFE-520TX device ID
+ */
+#define	DLINK_DEVICEID_520TX			0x4200
+
+/*
  * D-Link DFE-5280T device ID
  */
 #define	DLINK_DEVICEID_528T			0x4300