From 91986fd3d335a2ea651bc85cf5a03f2f61a2aa34 Mon Sep 17 00:00:00 2001 From: Philipp Kirchhofer Date: Sun, 18 Oct 2015 16:02:43 +0200 Subject: [PATCH] net: mv643xx_eth: Ensure proper data alignment in TSO TX path 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 Signed-off-by: David S. Miller --- drivers/net/ethernet/marvell/mv643xx_eth.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c index 960169efe636..c05fb794d1ff 100644 --- a/drivers/net/ethernet/marvell/mv643xx_eth.c +++ b/drivers/net/ethernet/marvell/mv643xx_eth.c @@ -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; -- 2.20.1