Re: [net-next PATCH v3 5/8] net: dsa: realtek: rtl8365mb: add VLAN support

[Mieczyslaw Nalewaj <namiltd@yahoo.com>]

On 5/7/2026 4:58 AM, Luiz Angelo Daros de Luca wrote:
> From: Alvin Šipraga <alsi@bang-olufsen.dk>
> 
> Realtek RTL8365MB switches (a.k.a. RTL8367C family) use two different
> structures for VLANs:
> 
> - VLAN4K: A full table with 4096 entries defining port membership and
>   tagging.
> - VLANMC: A smaller table with 32 entries used primarily for PVID
>   assignment.
> 
> In this hardware, a port's PVID must point to an index in the VLANMC
> table rather than a VID directly. Since the VLANMC table is limited to
> 32 entries, the driver implements a dynamic allocation scheme to
> maximize resource usage:
> 
> - VLAN4K is treated by the driver as the source of truth for membership.
> - A VLANMC entry is only allocated when a port is configured to use a
>   specific VID as its PVID.
> - VLANMC entries are deleted when no longer needed as a PVID by any port.
> 
> Although VLANMC has a members field, the switch only checks membership
> in the VLAN4K table. However, when a corresponding VLAN entry also exists
> in VLANMC, this driver keeps both membership configurations in sync.
> 
> VLANMC index 0, although a valid entry, is reserved in this driver as a
> neutral PVID value for ports not using a specific PVID.
> 
> In the subsequent RTL8367D switch family, VLANMC table was
> removed and PVID assignment was delegated to a dedicated set of
> registers.
> 
> All ports start isolated, forwarding exclusively to CPU ports, and
> with VLAN transparent, ignoring VLAN membership. Once a member in a
> bridge, the port isolation is expanded to include the bridge members.
> When that bridge enables VLAN filtering, the VLAN transparent feature is
> disabled, letting the switch filter based on VLAN setup.
> 
> The use of FIELD_PREP for reconstructing LO/HI values was suggested by
> Yury Norov.
> 
> Fix for vlan_setup and vlan_filtering was suggested by Abdulkader
> Alrezej.
> 
> Suggested-by: Yury Norov <ynorov@nvidia.com>
> Suggested-by: Abdulkader Alrezej <abdulkader.alrezej@gmail.com>
> Co-developed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
> Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
> Reviewed-by: Linus Walleij <linusw@kernel.org>
> Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Reviewed-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>