usb4bsd patch review

[M. Warner Losh]

In message: <200808210905.59150.hselasky at c2i.net>
            Hans Petter Selasky <hselasky at c2i.net> writes:
: USB audio is the only sound device I know about that is regularly plugged in 
: and out, which is causing this code path to be executed, unless you load 
: unload a sound module, which I think is very rarely done.

There's a number of CardBus sound cards that I've helped people debug
over the years.  Also, I know many people will load and unload the
sound driver as a way to keep power usage down since doing so puts the
device into D3 state.  I've fielded many bugs over the years where
people have issues with sound because they suddenly removed it while
things were playing.

Warner