netdev - [PATCH net-next 06/11] net: fec: transmit XDP frames in bulk

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Message-Id: <20260113032939.3705137-7-wei.fang@nxp.com>
Date: Tue, 13 Jan 2026 11:29:34 +0800
From: Wei Fang <wei.fang@....com>
To: shenwei.wang@....com,
	xiaoning.wang@....com,
	frank.li@....com,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	ast@...nel.org,
	daniel@...earbox.net,
	hawk@...nel.org,
	john.fastabend@...il.com,
	sdf@...ichev.me
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev,
	bpf@...r.kernel.org
Subject: [PATCH net-next 06/11] net: fec: transmit XDP frames in bulk

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@....com>
---
 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 0b114a68cd8e..f3e93598a27c 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1994,6 +1994,8 @@ 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:
@@ -2043,6 +2045,10 @@ 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[queue]);
+
 	return pkt_received;
 }
 
@@ -4033,9 +4039,6 @@ 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;
 }
 
@@ -4087,6 +4090,9 @@ 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