Re: [PATCH net 1/2] net: dsa: let drivers offload 8021q uppers on standalone ports

[Semih Baskan]

Hi Jonas,

On Wed, Aug 12, 2026 at 12:52 PM Jonas Gorski <jonas.gorski@xxxxxxxxx> wrote:
> I think the register description might be wrong here, because changing
> the VID to PVID for untagged packets is the default / expected
> behavior.
>
> The datasheet for switches I do have say it replaces it if the VID is not 0:

You are right, and the MDK text is wrong for this chip too. Measured
just now on the BCM53011, volatile write with a timed revert: with
CHANGE_1Q_VID set, tagged broadcast frames carrying a VID absent from
the VLAN table, which deliver 0 of 10 across a vlan-unaware bridge
with the bit clear, arrive 10 of 10 at the far port. They arrive
untagged: the VID is rewritten to the PVID, the frame is classified
into that VLAN, and the egress untag map strips the header. Clearing
the bit returns delivery to 0 of 10, and the untagged control ran 10
of 10 in every phase.

So the bit is a real ingress reclassifier with your datasheet's
semantics. The original VID does not survive to the wire, so it
cannot serve the 8021q upper case, as you presumed earlier.

Best regards,
Semih