>-----Original Message----- >From: Lennert Buytenhek [mailto:buytenh@xxxxxxxxxxxxxx] >Sent: Tuesday, June 08, 2010 8:09 PM >To: Saeed Bishara >Cc: linux-net@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >Subject: Re: [PATCH 1/2] mv643xx_eth: disable csum offloading >if the hw limited by max size > >On Sun, Jun 06, 2010 at 03:28:55PM +0300, Saeed Bishara wrote: > >> diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c >> index e345ec8..79243dd 100644 >> --- a/drivers/net/mv643xx_eth.c >> +++ b/drivers/net/mv643xx_eth.c >> @@ -289,6 +289,7 @@ struct mv643xx_eth_shared_private { >> unsigned int t_clk; >> int extended_rx_coal_limit; >> int tx_bw_control; >> + int tx_csum_limit; >> }; >> >> #define TX_BW_CONTROL_ABSENT 0 >> @@ -2468,6 +2469,14 @@ static int >mv643xx_eth_change_mtu(struct net_device *dev, int new_mtu) >> mv643xx_eth_recalc_skb_size(mp); >> tx_set_rate(mp, 1000000000, 16777216); >> >> + if (mp->shared->tx_csum_limit && dev->mtu > >mp->shared->tx_csum_limit) { >> + dev->features &= ~NETIF_F_IP_CSUM; >> + dev->vlan_features &= ~NETIF_F_IP_CSUM; >> + } else { >> + dev->features |= NETIF_F_IP_CSUM; >> + dev->vlan_features |= NETIF_F_IP_CSUM; >> + } > >I wonder if it would be better to still advertise NETIF_F_IP_CSUM in >this case, but just call skb_checksum_help() if skb->len is > dev->mtu >in txq_submit_skb(), like we do for the case where the ethernet header >is of an unsupported length -- that way, we'd still have hardware >checksum offload for TX packets that _do_ fit inside the hardware TX >fifo, e.g. when communicating with hosts on another subnet where the >default MTU is used. Goog idea, I'll add a check to skb->len > mp->shared->tx_csum_limit. > > >> diff --git a/include/linux/mv643xx_eth.h >b/include/linux/mv643xx_eth.h >> index cbbbe9b..7402718 100644 >> --- a/include/linux/mv643xx_eth.h >> +++ b/include/linux/mv643xx_eth.h >> @@ -19,6 +19,10 @@ struct mv643xx_eth_shared_platform_data { >> struct mbus_dram_target_info *dram; >> struct platform_device *shared_smi; >> unsigned int t_clk; >> + /* >> + * Max packet size for Tx IP/Layer 4 checksum (0 -> no limit) > >There's always a limit. :-) You might as well just fill in the right >values for orion5x/kw/dd/loki while you're at it. Right, kirkwood and dove are limited to 1600, the others to 9*1024. Don't know about loki. > > >thanks, >Lennert >-- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
