[TG3]: Fix probe failure due to invalid MAC address

Some older bootcode in some devices may report 0 MAC address in
SRAM when booting up from low power state. This patch fixes the
problem by checking for a valid MAC address in SRAM and falling back
to NVRAM if necessary.

Thanks to walt <wa1ter@myrealbox.com> for reporting the problem
and helping to debug it.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -10531,6 +10531,7 @@ static int __devinit tg3_get_device_address(struct tg3 *tp)
 {
 	struct net_device *dev = tp->dev;
 	u32 hi, lo, mac_offset;
+	int addr_ok = 0;
 
 #ifdef CONFIG_SPARC64
 	if (!tg3_get_macaddr_sparc(tp))
@@ -10560,9 +10561,13 @@ static int __devinit tg3_get_device_address(struct tg3 *tp)
 		dev->dev_addr[3] = (lo >> 16) & 0xff;
 		dev->dev_addr[4] = (lo >>  8) & 0xff;
 		dev->dev_addr[5] = (lo >>  0) & 0xff;
+
+		/* Some old bootcode may report a 0 MAC address in SRAM */
+		addr_ok = is_valid_ether_addr(&dev->dev_addr[0]);
 	}
+	if (!addr_ok) {
 		/* Next, try NVRAM. */
-	else if (!(tp->tg3_flags & TG3_FLG2_SUN_570X) &&
+		if (!(tp->tg3_flags & TG3_FLG2_SUN_570X) &&
 		    !tg3_nvram_read(tp, mac_offset + 0, &hi) &&
 		    !tg3_nvram_read(tp, mac_offset + 4, &lo)) {
 			dev->dev_addr[0] = ((hi >> 16) & 0xff);
@@ -10584,6 +10589,7 @@ static int __devinit tg3_get_device_address(struct tg3 *tp)
 			dev->dev_addr[1] = hi & 0xff;
 			dev->dev_addr[0] = (hi >> 8) & 0xff;
 		}
+	}
 
 	if (!is_valid_ether_addr(&dev->dev_addr[0])) {
 #ifdef CONFIG_SPARC64