Re: [PATCH 01/14] net: ethernet: mtk_eth_soc: account for vlan in rx header length

[Vladimir Oltean]

On Mon, Nov 07, 2022 at 07:54:39PM +0100, Felix Fietkau wrote:
> This may be needed for correct MTU settings on devices using DSA
> 
> Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> index 589f27ddc401..dcf2a0d5da33 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> @@ -29,7 +29,7 @@
>  #define MTK_TX_DMA_BUF_LEN_V2	0xffff
>  #define MTK_DMA_SIZE		512
>  #define MTK_MAC_COUNT		2
> -#define MTK_RX_ETH_HLEN		(ETH_HLEN + ETH_FCS_LEN)
> +#define MTK_RX_ETH_HLEN		(VLAN_ETH_HLEN + ETH_HLEN + ETH_FCS_LEN)

Commit title says account for VLAN (VLAN_HLEN, 4 bytes), code says add
VLAN_ETH_HLEN (18) more bytes.

Also, why is DSA mentioned in the commit message? Is accounting for VLAN
hlen not needed if DSA is not used? Why?

>  #define MTK_RX_HLEN		(NET_SKB_PAD + MTK_RX_ETH_HLEN + NET_IP_ALIGN)
>  #define MTK_DMA_DUMMY_DESC	0xffffffff
>  #define MTK_DEFAULT_MSG_ENABLE	(NETIF_MSG_DRV | \
> -- 
> 2.38.1
>