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Commit 84411f73 authored by Ezequiel Garcia's avatar Ezequiel Garcia Committed by David S. Miller
Browse files

net: mv643xx_eth: Avoid setting the initial TCP checksum 



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: default avatarEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0a8fa933

drivers/net/ethernet/marvell/mv643xx_eth.c

+6 −3
Original line number Diff line number Diff line
@@ -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");