Diffusion FreeBSD src repository d99eb8230eb7

rtwn: change the USB TX transfers to only do one pending transfer per endpoint
d99eb8230eb7
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Description

rtwn: change the USB TX transfers to only do one pending transfer per endpoint

I found I was getting constant device timeouts when doing anything
more complicated than a single SSH on laptop with RTL8811AU.

After digging into it, i found a variety of fun situations, including
traffic stalls that would recover w/ a shorter (1 second) USB transfer
timeout. However, the big one is a straight up hang of any TX endpoint
until the NIC was reset. The RX side kept going just fine; only the
TX endpoints would hang.

Reproducing it was easy - just start up a couple of traffic streams
on different WME AC's - eg a best effort + bulk transfer, like
browsing the web and doing an ssh clone - throw in a ping -i 0.1
to your gateway, and it would very quickly hit device timeouts every
couple of seconds.

I put everything into a single TX EP and the hangs went away.
Well, mostly.

So after some MORE digging, I found that this driver isn't checking
if the transfers are going into the correct EPs for the packet
WME access category / 802.11 TID; and would frequently be able
to schedule multiple transfers into the same endpoint.

Then there's a second problem - there's an array of endpoints
used for setting up the USB device, with .endpoint = UE_ADDR_ANY,
however they're also being setup with the same endpoint configured
in multiple transfer configs. Eg, a NIC with 3 or 4 bulk TX endpoints
will configure the BK and BE endpoints with the same physical endpoint
ID. This also leads to timed out transfers.

My /guess/ was that the firmware isn't happy with one or both of the
above, and so I solved both.

drop the USB transfer timeout to 1 second, not 5 seconds - that way we'll either get a 1 second traffic pause and USB transfer failure, or a 5 second device timeout. Having both the TX timeout and the USB transfer timeout made recovery from a USB transfer timeout (without a NIC reset) almost impossible.

enforce one transfer per endpoint;
separate pending/active buffer tracking per endpoint;
each endpoint now has its own TX callback to make sure the queue / end point ID is known;
and only frames from a given endpoint pending queue is going into the active queue and into that endpoint.
Finally, create a local wme2qid array and populate it with the endpoint mapping that ensures unique physical endpoint use.

Locally tested: