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net: calxedaxgmac: update ring buffer tx_head after barriers

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Ensure that the descriptor writes are visible before the ring buffer head
is updated. Since writel is a barrier, we can simply update the head after
the writel.

Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rob Herring 2013-08-30 16:49:23 -05:00 committed by David S. Miller
parent 1a1d4d2f30
commit ca32723afe
1 changed files with 2 additions and 1 deletions
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3
drivers/net/ethernet/calxeda/xgmac.c
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@ -1121,9 +1121,10 @@ static netdev_tx_t xgmac_xmit(struct sk_buff *skb, struct net_device *dev)
wmb();
desc_set_tx_owner(first, desc_flags | TXDESC_FIRST_SEG);
writel(1, priv->base + XGMAC_DMA_TX_POLL);
priv->tx_head = dma_ring_incr(entry, DMA_TX_RING_SZ);
writel(1, priv->base + XGMAC_DMA_TX_POLL);
if (dma_ring_space(priv->tx_head, priv->tx_tail, DMA_TX_RING_SZ) <
MAX_SKB_FRAGS)
netif_stop_queue(dev);