[PATCH] e1000: Implement a workaround for 82546 errata 10

Implement 82546 errata 10 --  first Tx descriptor cannot have more than 2015 byte of data in it or it could hang the transmitter.
Signed-off-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@intel.com>
Signed-off-by: Ganesh Venkatesan <ganesh.venkatesan@intel.com>
Signed-off-by: John Ronciak <john.ronciak@intel.com>
diff -up net-drivers-2.6/drivers/net/e1000/e1000_main.c net-drivers-2.6/drivers/net/e1000.new/e1000_main.c

drivers/net/e1000/e1000_main.c

@@ -1777,6 +1777,15 @@ e1000_tx_map(struct e1000_adapter *adapter, struct sk_buff *skb,
 		if(unlikely(mss && !nr_frags && size == len && size > 8))
 			size -= 4;
 #endif
+		/* work-around for errata 10 and it applies
+		 * to all controllers in PCI-X mode
+		 * The fix is to make sure that the first descriptor of a
+		 * packet is smaller than 2048 - 16 - 16 (or 2016) bytes
+		 */
+		if(unlikely((adapter->hw.bus_type == e1000_bus_type_pcix) &&
+		                (size > 2015) && count == 0))
+		        size = 2015;
+                                                                                
 		/* Workaround for potential 82544 hang in PCI-X.  Avoid
 		 * terminating buffers within evenly-aligned dwords. */
 		if(unlikely(adapter->pcix_82544 &&
@@ -1979,6 +1988,13 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 	if(adapter->pcix_82544)
 		count++;
 
+	/* work-around for errata 10 and it applies to all controllers 
+	 * in PCI-X mode, so add one more descriptor to the count
+	 */
+	if(unlikely((adapter->hw.bus_type == e1000_bus_type_pcix) &&
+			(len > 2015)))
+		count++;
+
 	nr_frags = skb_shinfo(skb)->nr_frags;
 	for(f = 0; f < nr_frags; f++)
 		count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size,