[BRLTTY] USB issues with Baum display under Linux

[Jason White]

I've been experiencing a few USB oddities lately. I checked the logs and
noticed the following.

The braille display powered down due to inactivity, which is normal. The log
entries then show:

Jun  8 09:42:25 jdc brltty[993]: USB bulk transfer error 84: Invalid or incomplete multibyte or wide character.
Jun  8 09:42:25 jdc brltty[993]: USB control transfer error 71: Protocol error.
Jun  8 09:42:25 jdc brltty[993]: USB control transfer error 71: Protocol error.
Jun  8 09:42:25 jdc kernel: [ 3015.646757] usb 5-1: usbfs: USBDEVFS_CONTROL failed cmd brltty rqt 64 rq 3 len 0 ret -71
Jun  8 09:42:25 jdc kernel: [ 3015.647759] usb 5-1: usbfs: USBDEVFS_CONTROL failed cmd brltty rqt 64 rq 3 len 0 ret -71
Jun  8 09:42:25 jdc brltty[993]: USB control transfer error 19: No such device.
Jun  8 09:42:25 jdc brltty[993]: USB control transfer error 19: No such device.
Jun  8 09:42:25 jdc brltty[993]: USB control transfer error 19: No such device.
Jun  8 09:42:30 jdc brltty[993]: Baum Braille Driver:
Jun  8 09:42:31 jdc brltty[993]: Short Packet: 50 02
Jun  8 09:42:31 jdc brltty[993]: Unexpected Packet: 40 24
Jun  8 09:42:43 jdc brltty[993]: Baum Powerdown: power switch
Jun  8 09:42:52 jdc brltty[993]: Baum Braille Driver:
Jun  8 09:42:52 jdc brltty[993]: Short Packet: 50 02

As can be seen from the logs above, the display powered up spontaneously at
this point and the driver re-started.

The kernel is 3.9.4 from Debian. I've been noticing hangs and disappearances
of BRLTTY lately (not exactly crashes, as there haven't been any segfaults),
so I'll be watching the logs more closely.

The BRLTTY version is 4.5-2 from Debian.

If there's any additional data you'd like me to collect or debugging to be
done, let me know.

Thanks as always for great software.