[PATCH net-next v1 4/4] net: lan966x: generate software timestamp just before the doorbell

[Horatiu Vultur]

The 05/08/2025 11:33, Jason Xing wrote:
> 
> From: Jason Xing <kernelxing at tencent.com>
> 
> Make sure the call of skb_tx_timestamp as close to the doorbell.
> 
> Signed-off-by: Jason Xing <kernelxing at tencent.com>
> ---
>  drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
> index 502670718104..e030f23e5145 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
> @@ -730,7 +730,6 @@ int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev)
>                 }
>         }
> 
> -       skb_tx_timestamp(skb);

Changing this will break the PHY timestamping because the frame gets
modified in the next line, meaning that the classify function will
always return PTP_CLASS_NONE.

Nacked-by: Horatiu Vultur <horatiu.vultur at microchip.com>

>         skb_push(skb, IFH_LEN_BYTES);
>         memcpy(skb->data, ifh, IFH_LEN_BYTES);
>         skb_put(skb, 4);
> @@ -768,6 +767,7 @@ int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev)
>                 next_dcb_buf->ptp = true;
> 
>         /* Start the transmission */
> +       skb_tx_timestamp(skb);
>         lan966x_fdma_tx_start(tx);
> 
>         return NETDEV_TX_OK;
> --
> 2.43.5
> 

-- 
/Horatiu