[PATCH 12/12] net: ll_temac: Enable DMA when ready, not before

[Esben Haabendal]

As soon as TAILDESCR_PTR is written, DMA transfers might start.
Let's ensure we are ready to receive DMA IRQ's before doing that.

Signed-off-by: Esben Haabendal <es...@geanix.com>
---
 drivers/net/ethernet/xilinx/ll_temac_main.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c 
b/drivers/net/ethernet/xilinx/ll_temac_main.c
index 5833f02..a230f6a 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -316,17 +316,21 @@ static int temac_dma_bd_init(struct net_device *ndev)
                    CHNL_CTRL_IRQ_EN | CHNL_CTRL_IRQ_ERR_EN |
                    CHNL_CTRL_IRQ_DLY_EN | CHNL_CTRL_IRQ_COAL_EN);
 
-       lp->dma_out(lp, RX_CURDESC_PTR,  lp->rx_bd_p);
-       lp->dma_out(lp, RX_TAILDESC_PTR,
-                      lp->rx_bd_p + (sizeof(*lp->rx_bd_v) * (RX_BD_NUM - 1)));
-       lp->dma_out(lp, TX_CURDESC_PTR, lp->tx_bd_p);
-
        /* Init descriptor indexes */
        lp->tx_bd_ci = 0;
        lp->tx_bd_next = 0;
        lp->tx_bd_tail = 0;
        lp->rx_bd_ci = 0;
 
+       /* Enable RX DMA transfers */
+       wmb();
+       lp->dma_out(lp, RX_CURDESC_PTR,  lp->rx_bd_p);
+       lp->dma_out(lp, RX_TAILDESC_PTR,
+                      lp->rx_bd_p + (sizeof(*lp->rx_bd_v) * (RX_BD_NUM - 1)));
+
+       /* Prepare for TX DMA transfer */
+       lp->dma_out(lp, TX_CURDESC_PTR, lp->tx_bd_p);
+
        return 0;
 
 out:
@@ -790,6 +794,7 @@ temac_start_xmit(struct sk_buff *skb, struct net_device 
*ndev)
        skb_tx_timestamp(skb);
 
        /* Kick off the transfer */
+       wmb();
        lp->dma_out(lp, TX_TAILDESC_PTR, tail_p); /* DMA start */
 
        return NETDEV_TX_OK;
-- 
2.4.11