USB causing boot to hang

I updates /usr/src to r355452, and updated by kernel and
world.  Upon rebooting, verbose boot messages susgests
the system is hanging when USB starts to attach.  With
the 3-week kernel verbose boot shows:

...
pcm4: <Realtek ALC889 (Rear Digital)> at nid 30 on hdaa1
pcm4: Playback:
pcm4:      Stream cap: 0x00000005 AC3 PCM
pcm4:         PCM cap: 0x000e05f0 16 20 24 bits, 32 44 48 88 96 192 KHz
pcm4:             DAC: 6
pcm4: 
pcm4:     nid=30 [pin: SPDIF-out (Grey Jack)]
pcm4:       + <- nid=6 [audio output] [src: pcm]
pcm4: 
pcm4: Mixer "vol" -> "none": child=0x00000010
pcm4: Mixer "pcm": parent="vol"
pcm4: Soft PCM mixer ENABLED
pcm4: Playback channel set is: Front Left, Front Right, 
pcm4: Playback channel matrix is: 2.0 (unknown)
usbus0: 5.0Gbps Super Speed USB v3.0
usbus1: 12Mbps Full Speed USB v1.0
...

end with a prompt on the console.  With today's kernel,
boot is hung after the last pcm4: message and no usbus0
is displayed.

The booting kernel/system is a 

% uname -a
FreeBSD 13.0-CURRENT #1 r354658: Wed Nov 13 11:23:32 PST 2019,  amd64

Again, the failing kernel is r 355452


-- 
Steve