[iwn] request to test: linkq, plcp, txrate fixes

[Adrian Chadd]

Hi!

I have a patch against iwn(4):

http://people.freebsd.org/~adrian/ath/20131024-iwn-1-fix-xmit-rate-plcp-linkq.diff

This does a few things:

* The multi-rate retry ("link quality" stuff) on iwn is a table, and I
think I broke it slightly when I implemented 11n rate control. This
disables it for now, at least until I / someone implements a replacement
table setup and linkq decision.

* get rid of the rate index stuff - it was used to decide a few things and
it was doing legacy-only rate index lookups. I've just removed it; it's not
needed.

* Teach the raw transmit path to use the new plcp lookup routine that sets
things up.

* Correctly implement 11g protection. Right now it was a bit of a hack and
it was not correct for 11a or 11n operation.

I still get transmit hangs on my 4965 but the "invalid rate" failures have
disappeared. But for some odd reason, the transmits completed but weren't
being marked as failed. I don't yet know why.

I'm also not sure why transmit is hanging; sometimes it looks like DMA
stalls somehow.

So - maybe this'll help with various 11n issues on iwn(4), maybe it won't.
I'm not sure yet. I'm trying to avoid taking ownership of iwn(4) but I
rather dislike the occasional 5100/4965 hangs..

Thanks,



-adrian