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net: mv643xx_eth: Avoid setting the initial TCP checksum

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As specified in the datasheet, the driver can set the "L4Chk_Mode" flag
(bit 10) in the Tx descriptor command/status to specify that a frame is not
IP fragmented and that the controller is in charge of generating the TCP/IP
checksum. This must be used together with the "GL4chk" flag (bit 17).

These two flags allow to avoid setting the initial TCP checksum in the l4i_chk
field of the Tx descriptor, which is needed to support software TSO.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ezequiel Garcia 2014-05-19 13:59:57 -03:00 committed by David S. Miller
parent 0a8fa93310
commit 84411f73b8
1 changed files with 6 additions and 3 deletions
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9
drivers/net/ethernet/marvell/mv643xx_eth.c
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@ -250,6 +250,7 @@ struct tx_desc {
#define GEN_TCP_UDP_CHECKSUM 0x00020000
#define UDP_FRAME 0x00010000
#define MAC_HDR_EXTRA_4_BYTES 0x00008000
#define GEN_TCP_UDP_CHK_FULL 0x00000400
#define MAC_HDR_EXTRA_8_BYTES 0x00000200
#define TX_IHL_SHIFT 11
@ -695,17 +696,19 @@ static int skb_tx_csum(struct mv643xx_eth_private *mp, struct sk_buff *skb,
if (tag_bytes & 8)
cmd |= MAC_HDR_EXTRA_8_BYTES;
cmd |= GEN_TCP_UDP_CHECKSUM |
cmd |= GEN_TCP_UDP_CHECKSUM | GEN_TCP_UDP_CHK_FULL |
GEN_IP_V4_CHECKSUM |
ip_hdr(skb)->ihl << TX_IHL_SHIFT;
/* TODO: Revisit this. With the usage of GEN_TCP_UDP_CHK_FULL
* it seems we don't need to pass the initial checksum. */
switch (ip_hdr(skb)->protocol) {
case IPPROTO_UDP:
cmd |= UDP_FRAME;
*l4i_chk = ntohs(sum16_as_be(udp_hdr(skb)->check));
*l4i_chk = 0;
break;
case IPPROTO_TCP:
*l4i_chk = ntohs(sum16_as_be(tcp_hdr(skb)->check));
*l4i_chk = 0;
break;
default:
WARN(1, "protocol not supported");