mv643xx_eth: enable hardware TX checksumming with vlan tags

Although mv643xx_eth has no hardware support for inserting a vlan
tag by twiddling some bits in the TX descriptor, it does support
hardware TX checksumming on packets where the IP header starts {a
limited set of values other than 14} bytes into the packet.

This patch sets mv643xx_eth's ->vlan_features to NETIF_F_SG |
NETIF_F_IP_CSUM, which prevents the stack from checksumming vlan'ed
packets in software, and if vlan tags are present on a transmitted
packet, notifies the hardware of this fact by toggling the right
bits in the TX descriptor.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 01dd3c505d25b783a091a7a8422c973e88a1a3a1..88bb1f1e8065166b8b9956daf7cfa17cf19e4ba5 100644 (file)
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -235,6 +235,8 @@ struct tx_desc {
 #define GEN_IP_V4_CHECKSUM             0x00040000
 #define GEN_TCP_UDP_CHECKSUM           0x00020000
 #define UDP_FRAME                      0x00010000
+#define MAC_HDR_EXTRA_4_BYTES          0x00008000
+#define MAC_HDR_EXTRA_8_BYTES          0x00000200
 
 #define TX_IHL_SHIFT                   11
 
@@ -757,12 +759,36 @@ static void txq_submit_skb(struct tx_queue *txq, struct sk_buff *skb)
        desc->buf_ptr = dma_map_single(NULL, skb->data, length, DMA_TO_DEVICE);
 
        if (skb->ip_summed == CHECKSUM_PARTIAL) {
-               BUG_ON(skb->protocol != htons(ETH_P_IP));
+               int mac_hdr_len;
+
+               BUG_ON(skb->protocol != htons(ETH_P_IP) &&
+                      skb->protocol != htons(ETH_P_8021Q));
 
                cmd_sts |= GEN_TCP_UDP_CHECKSUM |
                           GEN_IP_V4_CHECKSUM   |
                           ip_hdr(skb)->ihl << TX_IHL_SHIFT;
 
+               mac_hdr_len = (void *)ip_hdr(skb) - (void *)skb->data;
+               switch (mac_hdr_len - ETH_HLEN) {
+               case 0:
+                       break;
+               case 4:
+                       cmd_sts |= MAC_HDR_EXTRA_4_BYTES;
+                       break;
+               case 8:
+                       cmd_sts |= MAC_HDR_EXTRA_8_BYTES;
+                       break;
+               case 12:
+                       cmd_sts |= MAC_HDR_EXTRA_4_BYTES;
+                       cmd_sts |= MAC_HDR_EXTRA_8_BYTES;
+                       break;
+               default:
+                       if (net_ratelimit())
+                               dev_printk(KERN_ERR, &txq_to_mp(txq)->dev->dev,
+                                  "mac header length is %d?!\n", mac_hdr_len);
+                       break;
+               }
+
                switch (ip_hdr(skb)->protocol) {
                case IPPROTO_UDP:
                        cmd_sts |= UDP_FRAME;
@@ -2565,6 +2591,7 @@ static int mv643xx_eth_probe(struct platform_device *pdev)
         * have to map the buffers to ISA memory which is only 16 MB
         */
        dev->features = NETIF_F_SG | NETIF_F_IP_CSUM;
+       dev->vlan_features = NETIF_F_SG | NETIF_F_IP_CSUM;
 #endif
 
        SET_NETDEV_DEV(dev, &pdev->dev);