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net: mv643xx_eth: Ensure proper data alignment in TSO TX path

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The TX DMA engine requires that buffers with a size of 8 bytes or smaller
must be 64 bit aligned. This requirement may be violated when doing TSO,
as in this case larger skb frags can be broken up and transmitted in small
parts with then inappropriate alignment.

Fix this by checking for proper alignment before handing a buffer to the
DMA engine. If the data is misaligned realign it by copying it into the
TSO header data area.

Signed-off-by: Philipp Kirchhofer <philipp@familie-kirchhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Philipp Kirchhofer 2015-10-18 16:02:43 +02:00 committed by David S. Miller
parent f3c9f95056
commit 91986fd3d3
1 changed files with 17 additions and 5 deletions
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22
drivers/net/ethernet/marvell/mv643xx_eth.c
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@ -759,11 +759,23 @@ txq_put_data_tso(struct net_device *dev, struct tx_queue *txq,
desc->l4i_chk = 0;
desc->byte_cnt = length;
desc->buf_ptr = dma_map_single(dev->dev.parent, data,
length, DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(dev->dev.parent, desc->buf_ptr))) {
WARN(1, "dma_map_single failed!\n");
return -ENOMEM;
if (length <= 8 && (uintptr_t)data & 0x7) {
/* Copy unaligned small data fragment to TSO header data area */
memcpy(txq->tso_hdrs + txq->tx_curr_desc * TSO_HEADER_SIZE,
data, length);
desc->buf_ptr = txq->tso_hdrs_dma
+ txq->tx_curr_desc * TSO_HEADER_SIZE;
} else {
/* Alignment is okay, map buffer and hand off to hardware */
txq->tx_desc_mapping[tx_index] = DESC_DMA_MAP_SINGLE;
desc->buf_ptr = dma_map_single(dev->dev.parent, data,
length, DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(dev->dev.parent,
desc->buf_ptr))) {
WARN(1, "dma_map_single failed!\n");
return -ENOMEM;
}
}
cmd_sts = BUFFER_OWNED_BY_DMA;