> From: Kim Naru (
squat_rack@yahoo.com)
>
> Added support to offload TCP/UDP/IP checksum to the
> VIA Technologies VT6105M chip.
> Firstly, let the stack know this chip is capable of
> doing its own checksum(IPV4 only).
> Secondly offload checksum to VT6105M, if necessary.
>
>
> Verbose Mode:
>
> #1. Define 3 bits(18,19,20) in Transmit Descriptor 1
> of chip, which affect checksum processing.
> The prefix(TDES1) for the 3 variables is the short
> name for Transmit Descriptior 1.
> #2. In rhine_init_one(), if pci_rev >= VT6105M then
> set NETIF_F_IP_CSUM(see skbuff.h for details).
> #3. In rhine_start_tx() if NETIF_F_IP_CSUM is set AND
> the stack requires a checksum then
> set either bit 19(UDP),20(TCP) AND bit 18(IP).
>
> Note : The numbered items above(i.e.#1,#2,#3) denote
> pseudo code.
>
> This patch was developed and tested on Imedia
> linux-2.6.20 under a PC-Engines Alix System board
> (
www.pcengines.ch/alix.htm). It was tested(compilation
> only) on linux-2.6.22.2. The minor code change between
> 2.6.20 and 2.6.22 is the use of ip_hdr() in 2.26.22.
>
> In 2.6.20 :
> struct iphdr *ip = skb->nh.iph;
> In 2.6.22 :
> const struct iphdr *ip = ip_hdr(skb);
>
> Testing:
>
>
> ttcp,netperf ftp and top where used. There appears to
> be a small CPU utilization gain. Throughput results
> where more inconclusive.
>
> The data sheet used to get information is 'VT6105M
> Data Sheet, Revision 1.63 June21,2006'.
>
> Signed-off-by: Kim Naru (
squat_rack@yahoo.com)
>
> ---
>
>
> --- drivers/net/via-rhine.c 2007-08-17
> 00:24:33.000000000 -0700
> +++ drivers/net/via-rhine.c.orig 2007-08-15
> 05:03:20.000000000 -0700
> @@ -95,8 +95,6 @@ static const int
> multicast_filter_limit
> #include <linux/netdevice.h>
> #include <linux/etherdevice.h>
> #include <linux/skbuff.h>
> -#include <linux/in.h>
> -#include <linux/ip.h>
> #include <linux/init.h>
> #include <linux/delay.h>
> #include <linux/mii.h>
> @@ -345,9 +343,6 @@ struct tx_desc {
>
> /* Initial value for tx_desc.desc_length, Buffer size
> goes to bits 0-10 */
> #define TXDESC 0x00e08000
> -#define TDES1_TCPCK 0x00100000 /* Bit 20,
> Transmit Desc 1 (VT6105M Data Sheet 1.63) */
> -#define TDES1_UDPCK 0x00080000 /* Bit 19,
> Transmit Desc 1 (VT6105M Data Sheet 1.63) */
> -#define TDES1_IPCK 0x00040000 /* Bit 18,
> Transmit Desc 1 (VT6105M Data Sheet 1.63) */
>
> enum rx_status_bits {
> RxOK=0x8000, RxWholePkt=0x0300, RxErr=0x008F
> @@ -793,9 +788,6 @@ static int __devinit
> rhine_init_one(stru
> if (rp->quirks & rqRhineI)
> dev->features |=
> NETIF_F_SG|NETIF_F_HW_CSUM;
>
> - if (pci_rev >= VT6105M)
> - dev->features |= NETIF_F_IP_CSUM; /*
> tell stack chip does checksum */
> -
> /* dev->name not defined before
> register_netdev()! */
> rc = register_netdev(dev);
> if (rc)
> @@ -1270,20 +1262,6 @@ static int
> rhine_start_tx(struct sk_buff
>
> /* lock eth irq */
> spin_lock_irq(&rp->lock);
> -
> - if ((dev->features & NETIF_F_IP_CSUM) &&
> (skb->ip_summed == CHECKSUM_PARTIAL)) {
> - const struct iphdr *ip = ip_hdr(skb);
> -
> - /* offload checksum to chip. */
> -
> - if (ip->protocol == IPPROTO_TCP)
> - rp->tx_ring[entry].desc_length
> |= TDES1_TCPCK;
> - else if (ip->protocol == IPPROTO_UDP)
> - rp->tx_ring[entry].desc_length
> |= TDES1_UDPCK;
> - rp->tx_ring[entry].desc_length |=
> TDES1_IPCK;
> -
> - }
> -
> wmb();
> rp->tx_ring[entry].tx_status =
> cpu_to_le32(DescOwn);
> wmb();
