only support external PHYs (besides not connectable internal ones
which respond at the usual addresses, but which don't hurt if we
let them show up) and don't wedge when isolating PHYs. Actually,
this change special cases limiting PHYs to Am79C97{3,5,8}, for
which this driver doesn't implement swiching between the internal
and external PHYs, yet, and Am79C971, where isolating the external
PHY (at least in case it's a DP83840A) wedges the chip. Together
with sys/dev/mii/acphy.c rev. 1.21 this adds support for the
100baseFX port of AT-2700 series adaptors, which use two AC101,
one for the copper and one for the fibre port (there might be
variants which only use one PHY though).
- Fix a bug in the previous revision that prevented the address of
the used (external) PHY to be actually recorded.
- Don't bother to set if_mtu to ETHERMTU, ether_ifattach() does that.
MFC after: 1 week
d4c319bf3b