From 5e7bb38dc696b672b75de0539a75e776f023fe9b Mon Sep 17 00:00:00 2001 From: Jose Abreu Date: Mon, 17 Sep 2018 09:22:57 +0100 Subject: [PATCH] net: stmmac: Fixup the tail addr setting in xmit path [ Upstream commit 0431100b3d82c509729ece1ab22ada2484e209c1 ] Currently we are always setting the tail address of descriptor list to the end of the pre-allocated list. According to databook this is not correct. Tail address should point to the last available descriptor + 1, which means we have to update the tail address everytime we call the xmit function. This should make no impact in older versions of MAC but in newer versions there are some DMA features which allows the IP to fetch descriptors in advance and in a non sequential order so its critical that we set the tail address correctly. Signed-off-by: Jose Abreu Fixes: f748be531d70 ("stmmac: support new GMAC4") Cc: David S. Miller Cc: Joao Pinto Cc: Giuseppe Cavallaro Cc: Alexandre Torgue Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 1a9a382bf1c4b..bafbebeb0e001 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -2190,8 +2190,7 @@ static int stmmac_init_dma_engine(struct stmmac_priv *priv) priv->plat->dma_cfg, tx_q->dma_tx_phy, chan); - tx_q->tx_tail_addr = tx_q->dma_tx_phy + - (DMA_TX_SIZE * sizeof(struct dma_desc)); + tx_q->tx_tail_addr = tx_q->dma_tx_phy; priv->hw->dma->set_tx_tail_ptr(priv->ioaddr, tx_q->tx_tail_addr, chan); @@ -2963,6 +2962,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len); + tx_q->tx_tail_addr = tx_q->dma_tx_phy + (tx_q->cur_tx * sizeof(*desc)); priv->hw->dma->set_tx_tail_ptr(priv->ioaddr, tx_q->tx_tail_addr, queue); @@ -3178,9 +3178,11 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) if (priv->synopsys_id < DWMAC_CORE_4_00) priv->hw->dma->enable_dma_transmission(priv->ioaddr); - else + else { + tx_q->tx_tail_addr = tx_q->dma_tx_phy + (tx_q->cur_tx * sizeof(*desc)); priv->hw->dma->set_tx_tail_ptr(priv->ioaddr, tx_q->tx_tail_addr, queue); + } return NETDEV_TX_OK; -- 2.50.1