Question about usb devices and drvctl(8)

[buhrow%lothlorien.nfbcal.org@localhost (Brian Buhrow)]

        Hello.  I'm working on fixing some last minor bugs with  a new usb
driver for the Novatel 551L USB modems.  The bug I'm dealing with now
involves having the serial ports hang such that processes that have them
open get stuck in the ttyclose routine forever.  The way to get out of this
problem, at the moment, is to either reboot the system, unplug the modem
from the usb port and plug it back in, or use the drvctl(8) utility to
detach the new driver from the system.
        This last technique works quite well, except for one thing.  I've not
figured out a way to get the USB scanning process to wake up and reprobe
and reattach the device.  If I unplug the device and plug it back in, the
USB listening thread wakes up and probes and reattaches the device and all
is good.  Is there a way to trigger this behavior without actually
unplugging a device from the USB port?  It seems like this is exactly what
drvctl(8) is supposed to do, but I've not managed to figure out how to make
it go.  Has anyone else tried to do this and, if so, did they find a
solution?
        I'm using NetBSD-5, but even if it works in NetBSD-6 or later, that's
ok. I can bak port the functionality, I'm pretty sure.

-thanks
-Brian