[dpdk-dev] [PATCH 18/29] net/ena: remove memory barriers before doorbells

[Michal Krawczyk]

The doorbell code is already issuing the doorbell by using rte_write.
Because of that, there is no need to do that before calling the
function.

Signed-off-by: Michal Krawczyk <mk at semihalf.com>
Reviewed-by: Igor Chauskin <igorch at amazon.com>
Reviewed-by: Guy Tzalik <gtzalik at amazon.com>
---
 drivers/net/ena/ena_ethdev.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index b8bf31be7c..19a43400d5 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -1451,12 +1451,7 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 
 	/* When we submitted free recources to device... */
 	if (likely(i > 0)) {
-		/* ...let HW know that it can fill buffers with data
-		 *
-		 * Add memory barrier to make sure the desc were written before
-		 * issue a doorbell
-		 */
-		rte_wmb();
+		/* ...let HW know that it can fill buffers with data. */
 		ena_com_write_sq_doorbell(rxq->ena_com_io_sq);
 
 		rxq->next_to_use = next_to_use;
@@ -2389,7 +2384,6 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 			PMD_DRV_LOG(DEBUG, "llq tx max burst size of queue %d"
 				" achieved, writing doorbell to send burst\n",
 				tx_ring->id);
-			rte_wmb();
 			ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
 		}
 
@@ -2412,7 +2406,6 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	/* If there are ready packets to be xmitted... */
 	if (sent_idx > 0) {
 		/* ...let HW do its best :-) */
-		rte_wmb();
 		ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
 		tx_ring->tx_stats.doorbells++;
 		tx_ring->next_to_use = next_to_use;
-- 
2.20.1