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authorNiklas Cassel2018-02-26 22:47:07 +0100
committerDavid S. Miller2018-02-27 14:28:10 -0500
commit95eb930a40a0973f9b984d87a4986bb81f897ede (patch)
tree03bf3eaddc93e4baf247ad4938e932d1eff2c888 /drivers/net
parent15d2ee42a3087089e73ad52fd8c1b37ab496b87c (diff)
net: stmmac: use correct barrier between coherent memory and MMIO
The last memory barrier in stmmac_xmit()/stmmac_tso_xmit() is placed between a coherent memory write and a MMIO write: The own bit is written in First Desc (TSO: MSS desc or First Desc). <barrier> The DMA engine is started by a write to the tx desc tail pointer/ enable dma transmission register, i.e. a MMIO write. This barrier cannot be a simple dma_wmb(), since a dma_wmb() is only used to guarantee the ordering, with respect to other writes, to cache coherent DMA memory. To guarantee that the cache coherent memory writes have completed before we attempt to write to the cache incoherent MMIO region, we need to use the more heavyweight barrier wmb(). Signed-off-by: Niklas Cassel <niklas.cassel@axis.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/stmicro/stmmac/stmmac_main.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3b5e7b06e796..6dd04f237b2a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2997,7 +2997,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
* descriptor and then barrier is needed to make sure that
* all is coherent before granting the DMA engine.
*/
- dma_wmb();
+ wmb();
if (netif_msg_pktdata(priv)) {
pr_info("%s: curr=%d dirty=%d f=%d, e=%d, f_p=%p, nfrags %d\n",
@@ -3221,7 +3221,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
* descriptor and then barrier is needed to make sure that
* all is coherent before granting the DMA engine.
*/
- dma_wmb();
+ wmb();
}
netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);