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[PATCH] mv643xx_eth: Receive buffers require 8 byte alignment

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The Marvell mv643xx ethernet hardware requires that DMA buffers be
aligned to 8-byte boundaries.  This patch satisfies this requirement.
Buffers allocated by dev_alloc_skb() only have 4-byte alignment when
slab debugging is enabled.

Also, document that the 2-byte offset to align the IP packets on
receive is a hardware feature and is not tied to NET_IP_ALIGN.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>

 mv643xx_eth.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
This commit is contained in:
Dale Farnsworth 2006-01-16 16:51:22 -07:00 committed by Jeff Garzik
parent 16e0301831
commit b44cd57262
1 changed files with 9 additions and 3 deletions
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12
drivers/net/mv643xx_eth.c
View file

@ -57,7 +57,9 @@
/* Constants */
#define VLAN_HLEN 4
#define FCS_LEN 4
#define WRAP NET_IP_ALIGN + ETH_HLEN + VLAN_HLEN + FCS_LEN
#define DMA_ALIGN 8 /* hw requires 8-byte alignment */
#define HW_IP_ALIGN 2 /* hw aligns IP header */
#define WRAP HW_IP_ALIGN + ETH_HLEN + VLAN_HLEN + FCS_LEN
#define RX_SKB_SIZE ((dev->mtu + WRAP + 7) & ~0x7)
#define INT_CAUSE_UNMASK_ALL 0x0007ffff
@ -173,15 +175,19 @@ static void mv643xx_eth_rx_task(void *data)
struct mv643xx_private *mp = netdev_priv(dev);
struct pkt_info pkt_info;
struct sk_buff *skb;
int unaligned;
if (test_and_set_bit(0, &mp->rx_task_busy))
panic("%s: Error in test_set_bit / clear_bit", dev->name);
while (mp->rx_ring_skbs < (mp->rx_ring_size - 5)) {
skb = dev_alloc_skb(RX_SKB_SIZE);
skb = dev_alloc_skb(RX_SKB_SIZE + DMA_ALIGN);
if (!skb)
break;
mp->rx_ring_skbs++;
unaligned = (u32)skb->data & (DMA_ALIGN - 1);
if (unaligned)
skb_reserve(skb, DMA_ALIGN - unaligned);
pkt_info.cmd_sts = ETH_RX_ENABLE_INTERRUPT;
pkt_info.byte_cnt = RX_SKB_SIZE;
pkt_info.buf_ptr = dma_map_single(NULL, skb->data, RX_SKB_SIZE,
@ -192,7 +198,7 @@ static void mv643xx_eth_rx_task(void *data)
"%s: Error allocating RX Ring\n", dev->name);
break;
}
skb_reserve(skb, 2);
skb_reserve(skb, HW_IP_ALIGN);
}
clear_bit(0, &mp->rx_task_busy);
/*