[PATCH 4/5] e1000: Support sending custom Ethernet CRC.

@@ -1067,6 +1067,8 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
 	   (hw->mac_type != e1000_82547))
 		netdev->hw_features |= NETIF_F_TSO;
 
+	netdev->hw_features |= NETIF_F_NOFCS;
+
 	netdev->features |= netdev->hw_features;
 	netdev->hw_features |= NETIF_F_RXCSUM;
 

@@ -2692,6 +2694,7 @@ set_itr_now:
 #define E1000_TX_FLAGS_VLAN		0x00000002
 #define E1000_TX_FLAGS_TSO		0x00000004
 #define E1000_TX_FLAGS_IPV4		0x00000008
+#define E1000_TX_FLAGS_NO_FCS		0x00000010
 #define E1000_TX_FLAGS_VLAN_MASK	0xffff0000
 #define E1000_TX_FLAGS_VLAN_SHIFT	16
 

@@ -2993,6 +2996,9 @@ static void e1000_tx_queue(struct e1000_adapter *adapter,
 		txd_upper |= (tx_flags & E1000_TX_FLAGS_VLAN_MASK);
 	}
 
+	if (unlikely(tx_flags & E1000_TX_FLAGS_NO_FCS))
+		txd_lower &= ~(E1000_TXD_CMD_IFCS);
+
 	i = tx_ring->next_to_use;
 
 	while (count--) {

@@ -3007,6 +3013,10 @@ static void e1000_tx_queue(struct e1000_adapter *adapter,
 
 	tx_desc->lower.data |= cpu_to_le32(adapter->txd_cmd);
 
+	/* txd_cmd re-enables FCS, so we'll re-disable it here as desired. */
+	if (unlikely(tx_flags & E1000_TX_FLAGS_NO_FCS))
+		tx_desc->lower.data &= ~(cpu_to_le32(E1000_TXD_CMD_IFCS));
+
 	/* Force memory writes to complete before letting h/w
 	 * know there are new descriptors to fetch.  (Only
 	 * applicable for weak-ordered memory model archs,

@@ -3222,6 +3232,9 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
 	if (likely(skb->protocol == htons(ETH_P_IP)))
 		tx_flags |= E1000_TX_FLAGS_IPV4;
 
+	if (unlikely(skb->no_fcs && netdev->features & NETIF_F_NOFCS))
+		tx_flags |= E1000_TX_FLAGS_NO_FCS;
+
 	count = e1000_tx_map(adapter, tx_ring, skb, first, max_per_txd,
 	                     nr_frags, mss);
 

@@ -461,6 +461,7 @@ struct e1000_info {
 #define FLAG2_CHECK_PHY_HANG              (1 << 9)
 #define FLAG2_NO_DISABLE_RX               (1 << 10)
 #define FLAG2_PCIM2PCI_ARBITER_WA         (1 << 11)
+#define FLAG2_DFLT_CRC_STRIPPING          (1 << 12)
 
 #define E1000_RX_DESC_PS(R, i)	    \
 	(&(((union e1000_rx_desc_packet_split *)((R).desc))[i]))

@@ -936,8 +936,16 @@ static bool e1000_clean_rx_irq(struct e1000_ring *rx_ring, int *work_done,
 		}
 
 		/* adjust length to remove Ethernet CRC */
-		if (!(adapter->flags2 & FLAG2_CRC_STRIPPING))
-			length -= 4;
+		if (!(adapter->flags2 & FLAG2_CRC_STRIPPING)) {
+			/* If configured to store CRC, don't subtract FCS,
+			 * but keep the FCS bytes out of the total_rx_bytes
+			 * counter
+			 */
+			if (netdev->features & NETIF_F_RXFCS)
+				total_rx_bytes -= 4;
+			else
+				length -= 4;
+		}
 
 		total_rx_bytes += length;
 		total_rx_packets++;

@@ -1298,8 +1306,10 @@ static bool e1000_clean_rx_irq_ps(struct e1000_ring *rx_ring, int *work_done,
 						   PAGE_SIZE, DMA_FROM_DEVICE);
 
 			/* remove the CRC */
-			if (!(adapter->flags2 & FLAG2_CRC_STRIPPING))
-				l1 -= 4;
+			if (!(adapter->flags2 & FLAG2_CRC_STRIPPING)) {
+				if (!(netdev->features & NETIF_F_RXFCS))
+					l1 -= 4;
+			}
 
 			skb_put(skb, l1);
 			goto copydone;

@@ -1325,8 +1335,10 @@ static bool e1000_clean_rx_irq_ps(struct e1000_ring *rx_ring, int *work_done,
 		/* strip the ethernet crc, problem is we're using pages now so
 		 * this whole operation can get a little cpu intensive
 		 */
-		if (!(adapter->flags2 & FLAG2_CRC_STRIPPING))
-			pskb_trim(skb, skb->len - 4);
+		if (!(adapter->flags2 & FLAG2_CRC_STRIPPING)) {
+			if (!(netdev->features & NETIF_F_RXFCS))
+				pskb_trim(skb, skb->len - 4);
+		}
 
 copydone:
 		total_rx_bytes += skb->len;

@@ -5990,7 +6002,7 @@ static int e1000_set_features(struct net_device *netdev,
 		adapter->flags |= FLAG_TSO_FORCE;
 
 	if (!(changed & (NETIF_F_HW_VLAN_RX | NETIF_F_HW_VLAN_TX |
-			 NETIF_F_RXCSUM | NETIF_F_RXHASH)))
+			 NETIF_F_RXCSUM | NETIF_F_RXHASH | NETIF_F_RXFCS)))
 		return 0;
 
 	/*

@@ -6004,6 +6016,20 @@ static int e1000_set_features(struct net_device *netdev,
 		return -EINVAL;
 	}
 
+	if (changed & NETIF_F_RXFCS) {
+		if (features & NETIF_F_RXFCS) {
+			adapter->flags2 &= ~FLAG2_CRC_STRIPPING;
+		} else {
+			/* We need to take it back to defaults, which might mean
+			 * stripping is still disabled at the adapter level.
+			 */
+			if (adapter->flags2 & FLAG2_DFLT_CRC_STRIPPING)
+				adapter->flags2 |= FLAG2_CRC_STRIPPING;
+			else
+				adapter->flags2 &= ~FLAG2_CRC_STRIPPING;
+		}
+	}
+
 	netdev->features = features;
 
 	if (netif_running(netdev))

@@ -6203,6 +6229,7 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
 
 	/* Set user-changeable features (subset of all device features) */
 	netdev->hw_features = netdev->features;
+	netdev->hw_features |= NETIF_F_RXFCS;
 
 	if (adapter->flags & FLAG_HAS_HW_VLAN_FILTER)
 		netdev->features |= NETIF_F_HW_VLAN_FILTER;

@@ -463,10 +463,13 @@ void __devinit e1000e_check_options(struct e1000_adapter *adapter)
 		if (num_CrcStripping > bd) {
 			unsigned int crc_stripping = CrcStripping[bd];
 			e1000_validate_option(&crc_stripping, &opt, adapter);
-			if (crc_stripping == OPTION_ENABLED)
+			if (crc_stripping == OPTION_ENABLED) {
 				adapter->flags2 |= FLAG2_CRC_STRIPPING;
+				adapter->flags2 |= FLAG2_DFLT_CRC_STRIPPING;
+			}
 		} else {
 			adapter->flags2 |= FLAG2_CRC_STRIPPING;
+			adapter->flags2 |= FLAG2_DFLT_CRC_STRIPPING;
 		}
 	}
 	{ /* Kumeran Lock Loss Workaround */