On Wed, Jul 15, 2026 at 09:29:41AM +1000, Luke Howard wrote:

The driver decided whether a device has a dedicated ATU FID register
from its database count, taking the register path only when there were
more than 256 databases. The 88E6141/88E6341 have 256 databases but do
have the register, so they fell back to the legacy path and the FID
register was never written. Every FDB entry was then loaded into FID 0,
breaking VLAN aware bridging.

The number of databases does not imply whether the register is present.
Add an explicit atu_fid_reg flag, set it on every device that has the
register (all that previously matched the >256 heuristic, plus the
88E6141/88E6341), and key the register access off the flag instead of
the database count.

Fixes: a75961d0ebfd ("net: dsa: mv88e6xxx: Add support for ethernet switch 88E6341")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Luke Howard <redacted>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew