Re: [PATCH net-next v23 6/9] net: dsa: tag_mtk: add Airoha variant usage of this TAG

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] net: dsa: missing DSA_TAG_PROTO_AIROHA support in Mediatek/Airoha ethernet drivers
--

commit 3da7d110875eb668c591fb8186046c81cef009ee
Author: Christian Marangi <ansuelsmth@gmail.com>

net: dsa: tag_mtk: add Airoha variant usage of this TAG

Add variant of the MTK TAG for Airoha Switch and comments about difference
between Airoha AN8855 and Mediatek tag bitmap.

> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 5d12191b6f6f5..9824c63ad50b3 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -76,6 +77,7 @@ enum dsa_tag_protocol {
>  	DSA_TAG_PROTO_KSZ9893		= DSA_TAG_PROTO_KSZ9893_VALUE,
>  	DSA_TAG_PROTO_LAN9303		= DSA_TAG_PROTO_LAN9303_VALUE,
>  	DSA_TAG_PROTO_MTK		= DSA_TAG_PROTO_MTK_VALUE,
> +	DSA_TAG_PROTO_AIROHA		= DSA_TAG_PROTO_AIROHA_VALUE,

[Severity: High]
Does adding this new protocol variant break Ethernet drivers that explicitly
check for DSA_TAG_PROTO_MTK?

For example, in drivers/net/ethernet/airoha/airoha_eth.c:airoha_get_dsa_tag(),
failing to recognize the Airoha DSA protocol prevents extracting the tag for
hardware DMA descriptors, breaking transmission:

	if (dev->dsa_ptr->tag_ops->proto != DSA_TAG_PROTO_MTK)
		return 0;

Similarly, does this break PPE L2 flow offload in
drivers/net/ethernet/mediatek/mtk_ppe.c:mtk_ppe_check_skb() because it
rejects the Airoha protocol variant?

	if (!netdev_uses_dsa(skb->dev) ||
		    skb->dev->dsa_ptr->tag_ops->proto != DSA_TAG_PROTO_MTK)

And in drivers/net/ethernet/mediatek/mtk_ppe_offload.c:mtk_flow_get_dsa_port(),
will flow offloads targeting Airoha DSA ports fail or misroute?

	if (dp->cpu_dp->tag_ops->proto != DSA_TAG_PROTO_MTK)
		return -ENODEV;

Finally, in drivers/net/ethernet/mediatek/mtk_eth_soc.c:mtk_uses_dsa(), does it
disable GDMA hardware special tag parsing when an Airoha switch is connected?

	return netdev_uses_dsa(dev) &&
	       dev->dsa_ptr->tag_ops->proto == DSA_TAG_PROTO_MTK;

>  	DSA_TAG_PROTO_QCA		= DSA_TAG_PROTO_QCA_VALUE,
>  	DSA_TAG_PROTO_TRAILER		= DSA_TAG_PROTO_TRAILER_VALUE,
>  	DSA_TAG_PROTO_8021Q		= DSA_TAG_PROTO_8021Q_VALUE,

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260925182435.21207-1-ansuelsmth@gmail.com?part=6