Since DSA is supported on all devices, perhaps we should just have:

enum mv88e6xxx_edsa_support {
     MV88E6XXX_EDSA_UNSUPPORTED,
     MV88E6XXX_EDSA_UNDOCUMENTED,
     MV88E6XXX_EDSA_SUPPORTED,
};

Yes, that is O.K.
 

Do we also want to default to DSA on all devices unless there is a
DT-property saying something else? Using EDSA does not really give you
anything over bare tags anymore. You have fixed the tcpdump-issue, and
the tagger drivers have been unified so there should be no risk of any
regressions there either.

The regressions with be exactly what you are trying to fix here. A MAC
which does not understand the DSA tag and does the wrong thing, where
as currently it is using EDSA and working.

So i would keep things as they are by default.

   Andrew