4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jose Abreu Jose.Abreu@synopsys.com
[ 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 joabreu@synopsys.com Fixes: f748be531d70 ("stmmac: support new GMAC4") Cc: David S. Miller davem@davemloft.net Cc: Joao Pinto jpinto@synopsys.com Cc: Giuseppe Cavallaro peppe.cavallaro@st.com Cc: Alexandre Torgue alexandre.torgue@st.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- 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 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(struc
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
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;