Because of this we were not getting further interrupts for link state
changes, thus never went into iface UP state and thus could not transmit.
The only way out of this was an incoming packet generating an rx interrupt
and making us call into bge_link_upd.
Up to rev. 1.101, in bge_start_locked, we only returned instantly
if there was 'no link AND nothing queued for tx'. So with a packet queued
for tx, we hit the register scrubbing at the end of bge_start_locked
and were out fine. We simply lost a packet or two but got the interrupts
need to get into UP state.
With rev. 1.102 this was turned into 'if there is no link OR there is
nothing to send' (correct behaviour) and as long as there is no link
we never hit the register scrubbing and consequently never got the link UP.
What we do now is force an interrupt at the end of bge_ifmedia_upd_locked
so we will call bge_link_upd, clear the link state attention and get
further interrupts.
This helps to get the iface UP on an idle network or at least to get
it UP faster not depending on an rx intr anymore.
In case you could not get a DHCP lease or it took very long,
it was because of this.
It is unknown which chips are affected by this. ASIC rev. 0x2003 was the
most popular trouble candidate.
At least the fiber cards should have been working fine.
Which register to scrub is currently under discussion. The comitted
solution was tested and found to work for a lot of setups. It might
not help with MSI.
The reason why we end up in such a situation is entirely unknown.
PR: kern/111804
Tested by: phk, scottl at Y!
MFC after: 14 days
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