net: dsa: lantiq_gswip: remove legacy configure_vlan_while_not_filtering option

net: dsa: lantiq_gswip: remove legacy configure_vlan_while_not_filtering option

This driver doesn't support dynamic VLAN filtering changes, for simplicity.
It expects that on a port, either gswip_vlan_add_unaware() or
gswip_vlan_add_aware() is called, but not both.

When !br_vlan_enabled(), the configure_vlan_while_not_filtering = false
option is exactly what will prevent calls to gswip_port_vlan_add() from
being issued by DSA.

In fact, at the time these features were submitted:
https://patchwork.ozlabs.org/project/netdev/patch/20190501204506.21579-3-hauke@hauke-m.de/
"configure_vlan_while_not_filtering = false" did not even have a name,
it was implicit behaviour. It only became legacy in commit 54a0ed0df496
("net: dsa: provide an option for drivers to always receive bridge
VLANs").

Section "Bridge VLAN filtering" of Documentation/networking/switchdev.rst
describes the exact set of rules. Notably, the PVID of the port must
follow the VLAN awareness state of the bridge port. A VLAN-unaware
bridge port should not respond to the addition of a bridge VLAN with the
PVID flag. In fact, the pvid_change() test in
tools/testing/selftests/net/forwarding/bridge_vlan_unaware.sh tests
exactly this.

The lantiq_gswip driver indeed does not respond to the addition of PVID
VLANs while VLAN-unaware in the way described above, but only because of
configure_vlan_while_not_filtering. Our purpose here is to get rid of
configure_vlan_while_not_filtering, so we must add more complex logic
which follows the VLAN awareness state and walks through the Active VLAN
table entries, to find the index of the PVID register that should be
committed to hardware on each port.

As a side-effect of now having a proper implementation to assign the
PVID all the "VLAN upper: ..." tests of the local_termination.sh self-
tests which would previously all FAIL now all PASS (or XFAIL, but
that's ok).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Link: https://patch.msgid.link/47dab8a8b69ebb92624b9795b723114475d3fe4e.1760566491.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>