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Subject[PATCH 12/12] net: ll_temac: Enable DMA when ready, not before
Date
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 <esben@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
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