Stuck bwfm0

[John Klos <john%ziaspace.com@localhost>]

On NetBSD 9.99.93, on a Raspberry Pi Zero W, I'm using the build in 
wireless bwfm0:

[     1.761095] bwfm0: Firmware file default:    brcmfmac43430-sdio.bin
[     1.761095] bwfm0: Firmware file model-spec: brcmfmac43430-sdio.raspberrypi,model-zero-w.bin
...
[     1.791197] bwfm0: Found Firmware file: brcmfmac43430-sdio.bin
[     1.831309] bwfm0: NVRAM file default:    brcmfmac43430-sdio.txt
[     1.831309] bwfm0: NVRAM file model-spec: brcmfmac43430-sdio.raspberrypi,model-zero-w.txt
[     1.831309] bwfm0: Found NVRAM file: brcmfmac43430-sdio.raspberrypi,model-zero-w.txt
[     3.783668] bwfm0: CHIPACTIVE
[     3.883773] bwfm0: wl0: Oct 23 2017 03:55:53 version 7.45.98.38 (r674442 CY) FWID 01-e58d219f
[     3.883773] bwfm0: address b8:27:eb:fc:2a:fe

I see that scp'ing a few megabytes of data can freeze up bwfm0:

[  2179.739350] bwfm0: checksum error
[  2179.739350] bwfm0: checksum error
[  2179.749377] bwfm0: checksum error
[  2179.749377] bwfm0: checksum error
[  2179.749377] bwfm0: checksum error
[  2179.749377] bwfm0: checksum error
[  2383.456593] bwfm0: could not set mpc

Bringing the interface down and back up again doesn't fix anything (and 
takes a while), and "wlanctl -a" returns:

bwfm0: mac b8:27:eb:fc:2a:fe bss 00:00:00:00:00:00
	node flags 0005<bss,scan>
	ess <>
	chan 0 freq 0MHz flags 0000
	capabilities 0000
	beacon-interval 100 TU tsft 0 us
	rates
	assoc-id 0 assoc-failed 0 inactivity 300s
	rssi 0 txseq 0 rxseq 0

And "ifconfig bwfm0 list scan" gives:

ifconfig: SIOCS80211: Invalid argument

Once bwfm0 is in this state, is there any way to resurrect it short of a 
reboot? Is this a known issue?

Thanks,
John