ucc_geth: Don't needlessly change MAC settings in adjust_link()

If PHY doesn't have an IRQ, phylib would poll for link changes, and
would call adjust_link() every second. In that case we disable and
enable the controller every second.

Let's better check if there is actually anything changed, and, if so,
change the MAC settings.
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ucc_geth.c

@@ -1651,25 +1651,28 @@ static void adjust_link(struct net_device *dev)
 			ugeth->oldspeed = phydev->speed;
 		}
 
-		/*
-		 * To change the MAC configuration we need to disable the
-		 * controller. To do so, we have to either grab ugeth->lock,
-		 * which is a bad idea since 'graceful stop' commands might
-		 * take quite a while, or we can quiesce driver's activity.
-		 */
-		ugeth_quiesce(ugeth);
-		ugeth_disable(ugeth, COMM_DIR_RX_AND_TX);
-
-		out_be32(&ug_regs->maccfg2, tempval);
-		out_be32(&uf_regs->upsmr, upsmr);
-
-		ugeth_enable(ugeth, COMM_DIR_RX_AND_TX);
-		ugeth_activate(ugeth);
-
 		if (!ugeth->oldlink) {
 			new_state = 1;
 			ugeth->oldlink = 1;
 		}
+
+		if (new_state) {
+			/*
+			 * To change the MAC configuration we need to disable
+			 * the controller. To do so, we have to either grab
+			 * ugeth->lock, which is a bad idea since 'graceful
+			 * stop' commands might take quite a while, or we can
+			 * quiesce driver's activity.
+			 */
+			ugeth_quiesce(ugeth);
+			ugeth_disable(ugeth, COMM_DIR_RX_AND_TX);
+
+			out_be32(&ug_regs->maccfg2, tempval);
+			out_be32(&uf_regs->upsmr, upsmr);
+
+			ugeth_enable(ugeth, COMM_DIR_RX_AND_TX);
+			ugeth_activate(ugeth);
+		}
 	} else if (ugeth->oldlink) {
 			new_state = 1;
 			ugeth->oldlink = 0;