Re: [net-next PATCH v18 4/8] net: dsa: tag_mtk: add Airoha variant usage of this TAG

[Christian Marangi <ansuelsmth@gmail.com>]

On Wed, Sep 17, 2025 at 12:35:41PM +0300, Vladimir Oltean wrote:
> On Mon, Sep 15, 2025 at 12:45:40PM +0200, Christian Marangi wrote:
> > Add variant of the MTK TAG for Airoha Switch and comments about difference
> > between Airoha AN8855 and Mediatek tag bitmap.
> > 
> > Airoha AN8855 doesn't support controlling SA learning and Leaky VLAN
> > 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.
> > 
> > Rework the makefile, config and tag driver to better report to
> > external tool (like libpcap) the usage of this variant with a dedicated
> > "Airoha" name.
> > 
> > Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> > ---
> >  include/net/dsa.h |  2 ++
> >  net/dsa/Kconfig   | 11 +++++++++++
> >  net/dsa/Makefile  |  2 +-
> >  net/dsa/tag_mtk.c | 36 +++++++++++++++++++++++++++++++++---
> >  4 files changed, 47 insertions(+), 4 deletions(-)
> > 
> > diff --git a/include/net/dsa.h b/include/net/dsa.h
> > index d73ea0880066..bf03493e64ab 100644
> > --- a/include/net/dsa.h
> > +++ b/include/net/dsa.h
> > @@ -55,6 +55,7 @@ struct tc_action;
> >  #define DSA_TAG_PROTO_LAN937X_VALUE		27
> >  #define DSA_TAG_PROTO_VSC73XX_8021Q_VALUE	28
> >  #define DSA_TAG_PROTO_BRCM_LEGACY_FCS_VALUE	29
> > +#define DSA_TAG_PROTO_AIROHA_VALUE		30
> >  
> >  enum dsa_tag_protocol {
> >  	DSA_TAG_PROTO_NONE		= DSA_TAG_PROTO_NONE_VALUE,
> > @@ -69,6 +70,7 @@ 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,
> >  	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,
> > diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
> > index 869cbe57162f..7d63ecda25c8 100644
> > --- a/net/dsa/Kconfig
> > +++ b/net/dsa/Kconfig
> > @@ -98,12 +98,23 @@ config NET_DSA_TAG_EDSA
> >  	  Say Y or M if you want to enable support for tagging frames for the
> >  	  Marvell switches which use EtherType DSA headers.
> >  
> > +config NET_DSA_TAG_MTK_COMMON
> > +	tristate
> > +
> >  config NET_DSA_TAG_MTK
> >  	tristate "Tag driver for Mediatek switches"
> > +	select NET_DSA_TAG_MTK_COMMON
> >  	help
> >  	  Say Y or M if you want to enable support for tagging frames for
> >  	  Mediatek switches.
> >  
> > +config NET_DSA_TAG_AIROHA
> > +	tristate "Tag driver for Airoha switches"
> > +	select NET_DSA_TAG_MTK_COMMON
> > +	help
> > +	  Say Y or M if you want to enable support for tagging frames for
> > +	  Airoha switches.
> > +
> >  config NET_DSA_TAG_KSZ
> >  	tristate "Tag driver for Microchip 8795/937x/9477/9893 families of switches"
> >  	help
> > diff --git a/net/dsa/Makefile b/net/dsa/Makefile
> > index 555c07cfeb71..7aba189a715c 100644
> > --- a/net/dsa/Makefile
> > +++ b/net/dsa/Makefile
> > @@ -27,7 +27,7 @@ obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
> >  obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
> >  obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
> >  obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
> > -obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
> > +obj-$(CONFIG_NET_DSA_TAG_MTK_COMMON) += tag_mtk.o
> >  obj-$(CONFIG_NET_DSA_TAG_NONE) += tag_none.o
> >  obj-$(CONFIG_NET_DSA_TAG_OCELOT) += tag_ocelot.o
> >  obj-$(CONFIG_NET_DSA_TAG_OCELOT_8021Q) += tag_ocelot_8021q.o
> > diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
> > index b670e3c53e91..32befcbdf4be 100644
> > --- a/net/dsa/tag_mtk.c
> > +++ b/net/dsa/tag_mtk.c
> > @@ -11,6 +11,7 @@
> >  #include "tag.h"
> >  
> >  #define MTK_NAME		"mtk"
> > +#define AIROHA_NAME		"airoha"
> >  
> >  #define MTK_HDR_LEN		4
> >  #define MTK_HDR_XMIT_UNTAGGED		0
> > @@ -18,6 +19,9 @@
> >  #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.
> > + */
> >  #define MTK_HDR_XMIT_SA_DIS		BIT(6)
> >  
> >  static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
> > @@ -94,6 +98,7 @@ static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev)
> >  	return skb;
> >  }
> >  
> > +#if IS_ENABLED(CONFIG_NET_DSA_TAG_MTK)
> >  static const struct dsa_device_ops mtk_netdev_ops = {
> >  	.name		= MTK_NAME,
> >  	.proto		= DSA_TAG_PROTO_MTK,
> > @@ -102,8 +107,33 @@ static const struct dsa_device_ops mtk_netdev_ops = {
> >  	.needed_headroom = MTK_HDR_LEN,
> >  };
> >  
> > -MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
> > -MODULE_LICENSE("GPL");
> > +DSA_TAG_DRIVER(mtk_netdev_ops);
> >  MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
> > +#endif
> >  
> > -module_dsa_tag_driver(mtk_netdev_ops);
> > +#if IS_ENABLED(CONFIG_NET_DSA_TAG_AIROHA)
> > +static const struct dsa_device_ops airoha_netdev_ops = {
> > +	.name		= AIROHA_NAME,
> > +	.proto		= DSA_TAG_PROTO_AIROHA,
> > +	.xmit		= mtk_tag_xmit,
> > +	.rcv		= mtk_tag_rcv,
> > +	.needed_headroom = MTK_HDR_LEN,
> > +};
> > +
> > +DSA_TAG_DRIVER(airoha_netdev_ops);
> > +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_AIROHA, AIROHA_NAME);
> > +#endif
> > +
> > +static struct dsa_tag_driver *dsa_tag_driver_array[] =	{
> > +#if IS_ENABLED(CONFIG_NET_DSA_TAG_MTK)
> > +	&DSA_TAG_DRIVER_NAME(mtk_netdev_ops),
> > +#endif
> > +#if IS_ENABLED(CONFIG_NET_DSA_TAG_AIROHA)
> > +	&DSA_TAG_DRIVER_NAME(airoha_netdev_ops),
> > +#endif
> 
> Unless the few tens of bytes saved matter on OpenWRT, I think this is
> overkill (and you went too far with my previous suggestion).
> Two Kconfig options are unnecessary from a maintainance point of view
> (and config NET_DSA_AN8855 isn't even selecting the correct one!).
> I suggest you register both tag drivers as part of CONFIG_NET_DSA_TAG_MTK,
> at least until the differences increase to justify a new option.
>

Ok, was following the pattern done by the other. Will drop the
additional kconfig.

> > +};
> > +
> > +module_dsa_tag_drivers(dsa_tag_driver_array);
> > +
> > +MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
> > +MODULE_LICENSE("GPL");
> > -- 
> > 2.51.0
> > 
> 

-- 
	Ansuel