[net-next PATCH v16 10/10] net: dsa: tag_mtk: add comments about Airoha usage of this TAG

[Vladimir Oltean]

On Tue, Sep 09, 2025 at 02:43:41AM +0200, Christian Marangi wrote:
> Add comments about difference between Airoha AN8855 and Mediatek tag
> bitmap.
> 
> Airoha AN88555 doesn't support controlling SA learning and Leaky VLAN

Is there an extra 5 in AN88555?

> from tag. Although these bits are not used (and even not defined for
> Leaky VLAN), it's worth to add comments for these difference to prevent
> any kind of regression in the future if ever these bits will be used.
> 
> Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
> ---
>  net/dsa/tag_mtk.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
> index b670e3c53e91..ac3f956abe39 100644
> --- a/net/dsa/tag_mtk.c
> +++ b/net/dsa/tag_mtk.c
> @@ -18,6 +18,9 @@
>  #define MTK_HDR_XMIT_TAGGED_TPID_88A8	2
>  #define MTK_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
>  #define MTK_HDR_XMIT_DP_BIT_MASK	GENMASK(5, 0)
> +/* AN8855 doesn't support SA_DIS and Leaky VLAN
> + * control in tag as these bits doesn't exist.
> + */

I think it would be good to present the AN8855 tag using a different
string, so that libpcap knows it shouldn't decode these bits. The code
can be reused for now.

>  #define MTK_HDR_XMIT_SA_DIS		BIT(6)
>  
>  static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
> -- 
> 2.51.0
>