Perform skb_tx_timestamp before transferring ownership
This shrinks the window for 'tx int lost'
If the packet is transmitted and napi clears the tx interrupt
before the txq->bd.cur assignment, then the tx interrupt is
effectively lost.
Signed-off-by: Troy Kisky <troy.ki...@boundarydevices.com>
---
drivers/net/ethernet/freescale/fec_main.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
diff --git a/drivers/net/ethernet/freescale/fec_main.c
b/drivers/net/ethernet/freescale/fec_main.c
index 9da2c6d..512b1ad 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -510,27 +510,24 @@ static int fec_enet_txq_submit_skb(struct
fec_enet_priv_tx_q *txq,
index = fec_enet_get_bd_index(last_bdp, &txq->bd);
/* Save skb pointer */
txq->tx_skbuff[index] = skb;
+ last_bdp = fec_enet_get_nextdesc(last_bdp, &txq->bd);
+ skb_tx_timestamp(skb);
/* Make sure the updates to rest of the descriptor are performed before
* transferring ownership.
*/
wmb();
- /* Send it on its way. Tell FEC it's ready, interrupt when done,
- * it's the last BD of the frame, and to put the CRC on the end.
+ /* Send it on its way. Transfer ownership
+ * Make sure the update to bdp and tx_skbuff are performed before
+ * the update to txq->bd.cur.
+ * Keep window for interrupt between the next 3 lines as small as
+ * possible, to avoid "tx int lost" in case no more tx interrupts
+ * happen within 2 seconds.
*/
bdp->cbd_sc = status;
-
- /* If this was the last BD in the ring, start at the beginning again. */
- bdp = fec_enet_get_nextdesc(last_bdp, &txq->bd);
-
- skb_tx_timestamp(skb);
-
- /* Make sure the update to bdp and tx_skbuff are performed before
- * txq->bd.cur.
- */
wmb();
- txq->bd.cur = bdp;
+ txq->bd.cur = last_bdp;
/* Trigger transmission start */
writel(0, txq->bd.reg_desc_active);
@@ -719,12 +716,12 @@ static int fec_enet_txq_submit_tso(struct
fec_enet_priv_tx_q *txq,
* transferring ownership.
*/
wmb();
- /* Send it on its way. Tell FEC it's ready, interrupt when done,
+ /* Send it on its way. Transfer ownership
+ * Keep window for interrupt between the next 3 lines as small as
+ * possible, to avoid "tx int lost" in case no more tx interrupts
+ * happen within 2 seconds.
*/
first_bdp->cbd_sc = status;
- /* Make sure ownership is transferred before the
- * update to txq->bd.cur.
- */
wmb();
txq->bd.cur = bdp;
--
2.5.0
