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Commit b44cd572 authored by Dale Farnsworth's avatar Dale Farnsworth Committed by Jeff Garzik
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[PATCH] mv643xx_eth: Receive buffers require 8 byte alignment 



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: default avatarDale Farnsworth <dale@farnsworth.org>

 mv643xx_eth.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent 16e03018

drivers/net/mv643xx_eth.c

+9 −3
Original line number Diff line number Diff line
@@ -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);

	/*