Re: [Qemu-devel] [PATCH] alsa broken when the host is suspended (or hibernated)

["Bjørn Mork" <bjorn@mork.no>]

Bjørn Mork <bjorn@mork.no> writes:

> I tried your modified patch with Windows XP as a client, using the
> Windows "Sound Recorder" app for testing audio capture.  I have it
> working up until the host is suspended, but cannot make it work after
> resuming.  Nothing is captured and nothing is logged to the QEMU
> monitor. The "Sound Recorder" app just sits there after pressing record,
> without ever changing the stream position from 0,00 sec.

I added a few debug printf's and found that the problem is that
alsa_get_avail() will report 0 consistently after suspend.  Thus, we end
up silently returning before ever trying to snd_pcm_readi() anything:

    avail = alsa_get_avail (alsa->handle);
    decr = audio_MIN (dead, avail);
    if (!decr) {
        return 0;
    }


I don't know how to best fix this. We probably need to add some code
triggering ESTRPIPE when the driver is suspended, even if
alsa_get_avail() returns 0.  But I hesitate, as that seems rather
inefficent just for a special case like suspend/resume.



Bjørn