[PATCH v2 net-next 07/14] net: fec: transmit XDP frames in bulk

[Wei Fang]

Currently, the driver writes the ENET_TDAR register for every XDP frame
to trigger transmit start. Frequent MMIO writes consume more CPU cycles
and may reduce XDP TX performance, so transmit XDP frames in bulk.

Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
---
 drivers/net/ethernet/freescale/fec_main.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 251191ab99b3..52abeeb50dda 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2006,6 +2006,8 @@ static int fec_enet_rx_queue_xdp(struct fec_enet_private *fep, int queue,
 				rxq->stats[RX_XDP_TX_ERRORS]++;
 				fec_xdp_drop(rxq, &xdp, sync);
 				trace_xdp_exception(ndev, prog, XDP_TX);
+			} else {
+				xdp_res |= FEC_ENET_XDP_TX;
 			}
 			break;
 		default:
@@ -2055,6 +2057,10 @@ static int fec_enet_rx_queue_xdp(struct fec_enet_private *fep, int queue,
 	if (xdp_res & FEC_ENET_XDP_REDIR)
 		xdp_do_flush();
 
+	if (xdp_res & FEC_ENET_XDP_TX)
+		/* Trigger transmission start */
+		fec_txq_trigger_xmit(fep, fep->tx_queue[tx_qid]);
+
 	return pkt_received;
 }
 
@@ -4036,9 +4042,6 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep,
 
 	txq->bd.cur = bdp;
 
-	/* Trigger transmission start */
-	fec_txq_trigger_xmit(fep, txq);
-
 	return 0;
 }
 
@@ -4088,6 +4091,9 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
 		sent_frames++;
 	}
 
+	if (sent_frames)
+		fec_txq_trigger_xmit(fep, txq);
+
 	__netif_tx_unlock(nq);
 
 	return sent_frames;
-- 
2.34.1