uaudio in full duplex

Hans Petter Selasky hselasky at
Thu Apr 28 06:47:06 PDT 2005

On Friday 22 April 2005 06:39, Kazuhito HONDA wrote:
> 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.

What does the error messages say? It might be a bug in the UHCI driver, 
because it does currently not check when isochronous transfers are 
inserted in time !

  Hans Petter Selasky

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