uaudio in full duplex

[Kazuhito HONDA]

Hello, 

the uaudio driver doesn't allow USB devices to
open playback and record channel pipe, simultaneously,
if in FreeBSD-stable, at line 3650 of uaudio.c as below:

        if ((sc->sc_playchan.pipe != NULL) || (sc->sc_recchan.pipe != NULL))
                return (-1);

If you do comment-out it, you may be able to read and write several time.
But USB low-level driver soon freezes with eternal errors messages.
I haven't found its cause.  

Sincerely,
Kazuhito HONDA