On Tue, Jan 13, 2026 at 11:29:34AM +0800, Wei Fang wrote:
> 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@nxp.com>
> ---
Did you test light loading case? Any unexpected latency happen? sometime
missing trigger is hard to find when heavy loading.
Frank
> 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
>