EMAC driver: fix bug - invalidate data cache of new_skb->data range when cache is WB

It prevents overwritting new data from DMA.
Signed-off-by: Alexey Demin <bf53x@ya.ru>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bfin_mac.c

@@ -651,6 +651,12 @@ static void bf537mac_rx(struct net_device *dev)
 	current_rx_ptr->skb = new_skb;
 	current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
 
+	/* Invidate the data cache of skb->data range when it is write back
+	 * cache. It will prevent overwritting the new data from DMA
+	 */
+	blackfin_dcache_invalidate_range((unsigned long)new_skb->head,
+					 (unsigned long)new_skb->end);
+
 	len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
 	skb_put(skb, len);
 	blackfin_dcache_invalidate_range((unsigned long)skb->head,