From: Dale Farnsworth <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Index: linux-2.6-mv643xx_enet/drivers/net/mv643xx_eth.c
===================================================================
--- linux-2.6-mv643xx_enet.orig/drivers/net/mv643xx_eth.c
+++ linux-2.6-mv643xx_enet/drivers/net/mv643xx_eth.c
@@ -55,7 +55,9 @@
/* 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
@@ -171,15 +173,19 @@ static void mv643xx_eth_rx_task(void *da
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,
@@ -190,7 +196,7 @@ static void mv643xx_eth_rx_task(void *da
"%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);
/*
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
