[dpdk-dev] [PATCH] net/thunderx: Block sq door writes on zero pkts

[Kiran Kumar]

With current code, we are performing sq door writes even with 0 pkts.
this will create pressure on register bus. This patch will block these
writes.

Fixes: 1c421f18e0 ("net/thunderx: add single and multi-segment Tx")

Signed-off-by: Kiran Kumar <kkokkilagadda at caviumnetworks.com>
---
 drivers/net/thunderx/nicvf_rxtx.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/thunderx/nicvf_rxtx.c b/drivers/net/thunderx/nicvf_rxtx.c
index 72305d9..8075a8e 100644
--- a/drivers/net/thunderx/nicvf_rxtx.c
+++ b/drivers/net/thunderx/nicvf_rxtx.c
@@ -162,12 +162,14 @@ nicvf_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 		free_desc -= TX_DESC_PER_PKT;
 	}
 
-	sq->tail = tail;
-	sq->xmit_bufs += i;
-	rte_wmb();
+	if (likely(i)) {
+		sq->tail = tail;
+		sq->xmit_bufs += i;
+		rte_wmb();
 
-	/* Inform HW to xmit the packets */
-	nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
+		/* Inform HW to xmit the packets */
+		nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
+	}
 	return i;
 }
 
-- 
2.7.4