kern/54070: urtwn(4) does not work on OHCI

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         54070
>Category:       kern
>Synopsis:       urtwn(4) does not work on OHCI
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 24 10:55:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current (8.99.36)
>Organization:

>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

I have an RTL8188EU based USB WiFi adapter that works when attached to
a high-speed USB port driven by an EHCI controller (for some value of
"works").  However, when I attach it to a full-speed USB port on a NEC
Versa DayLite laptop, which uses an OHCI controller, or if I attach it
to a high-speed EHCI/OHCI port on a desktop through a full-speed hub
so that it gets routed to the OHCI companion controller, it can't
connect to the WiFi network.

My current minimal test case involves setting up an open network
(no encryption), plugging the adapter into the USB port or hub,
and simply running

  ifconfig urtwn0 ssid insert-ssid-here up

The driver attaches successfully:

  urtwn0 at uhub14 port 2
  urtwn0: Realtek (0xbda) 802.11n NIC (0x179), rev 2.00/0.00, addr 3
  urtwn0: MAC/BB RTL8188EU, RF 6052 1T1R, address 00:e0:4c:81:88:10
  urtwn0: 1 rx pipe, 2 tx pipes
  urtwn0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
  urtwn0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps

but when I try to inspect the state of the interface by repeatedly
running "ifconfig urtwn0", the output alternates between the following
two states on about a 10-second cycle.  This half-cycle lasts about 3
second:

   urtwn0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
           ssid insert-ssid-here
           powersave off
           bssid dc:ee:06:8e:3e:f5 chan 1
           address: 00:e0:4c:81:88:10
           media: IEEE802.11 autoselect (OFDM54 mode 11g)
           status: no network

And this one, about 7 seconds:

   urtwn0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
           ssid ""
           powersave off
           address: 00:e0:4c:81:88:10
           media: IEEE802.11 autoselect (OFDM54 mode 11g)
           status: no network

That is, the ssid and bssid come and go, but it always says "no network".

In the access point's display of connected clients, the NetBSD client
is continuously present, but the connection duration field resets to
zero every time it reaches about 30 seconds.

>How-To-Repeat:

>Fix: