[PATCH net RFC] net: dsa: mt7530: fix link-local frames that ingress vlan filtering ports

[Vladimir Oltean]

On Thu, Feb 01, 2024 at 10:13:39PM +0300, Arınç ÜNAL via B4 Relay wrote:
> One remaining limitation is that the ingress port must have a PVID assigned
> to it for the frame to be trapped to the CPU port. A PVID is set by default
> on vlan aware and vlan unaware ports. However, when the network interface
> that pertains to the ingress port is attached to a vlan_filtering enabled
> bridge, the user can remove the PVID assignment from it which would prevent
> the link-local frames from being trapped to the CPU port.
> 
> Signed-off-by: Arınç ÜNAL <arinc.unal at arinc9.com>
> ---
> I couldn't figure out a way to bypass VLAN table lookup for link-local
> frames to directly trap them to the CPU port. The CPU port is hardcoded for
> MT7530. For MT7531 and the switch on the MT7988 SoC, it depends on the port
> matrix to choose the CPU port to trap the frames to. Port matrix and VLAN
> table seem to go hand in hand so I don't know if this would even be
> possible.
> 
> If possible to implement, link-local frames must not be influenced by the
> VLAN table. They must always be trapped to the CPU port, and trapped
> untagged.

Isn't this, in effect, what the "Leaky VLAN Enable" bit does?