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mv643xx_eth: enforce multiple-of-8-bytes receive buffer size restriction

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The mv643xx_eth hardware ignores the lower three bits of the buffer
size field in receive descriptors, causing the reception of full-sized
packets to fail at some MTUs.  Fix this by rounding the size of
allocated receive buffers up to a multiple of eight bytes.

While we are at it, add a bit of extra space to each receive buffer so
that we can handle multiple vlan tags on ingress.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
This commit is contained in:
Lennert Buytenhek 2008-08-24 03:00:20 +02:00 committed by Lennert Buytenhek
parent 9e1f377242
commit abe787170b
1 changed files with 13 additions and 5 deletions
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18
drivers/net/mv643xx_eth.c
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@ -474,11 +474,19 @@ static void rxq_refill(struct rx_queue *rxq)
/*
* Reserve 2+14 bytes for an ethernet header (the
* hardware automatically prepends 2 bytes of dummy
* data to each received packet), 4 bytes for a VLAN
* header, and 4 bytes for the trailing FCS -- 24
* bytes total.
* data to each received packet), 16 bytes for up to
* four VLAN tags, and 4 bytes for the trailing FCS
* -- 36 bytes total.
*/
skb_size = mp->dev->mtu + 24;
skb_size = mp->dev->mtu + 36;
/*
* Make sure that the skb size is a multiple of 8
* bytes, as the lower three bits of the receive
* descriptor's buffer size field are ignored by
* the hardware.
*/
skb_size = (skb_size + 7) & ~7;
skb = dev_alloc_skb(skb_size + dma_get_cache_alignment() - 1);
if (skb == NULL)
@ -552,7 +560,7 @@ static int rxq_process(struct rx_queue *rxq, int budget)
spin_unlock_irqrestore(&mp->lock, flags);
dma_unmap_single(NULL, rx_desc->buf_ptr + 2,
mp->dev->mtu + 24, DMA_FROM_DEVICE);
rx_desc->buf_size, DMA_FROM_DEVICE);
rxq->rx_desc_count--;
rx++;