On Sun, 7 Oct 2007, Mike Gorse wrote: > > > I posted last week because I am getting lockups when portaudio > > > calls > > > snd_pcm_drain, and snd_pcm_rate_drain calls snd_pcm_wait on its > > > slave. > > > > > > Now that I've looked at this more, I'm seeing that it involves > > > dmix, since > > > a dmix plugin is behind the rate plugin. > > > > > > The dmix code in alsa-lib is setting a xrun state because > > > snd_pcm_mmap_playback_avail returns a large value. > > > > > > snd_pcm_wait is then called on the slave of the rate pcm, which is > > > a pcm > > > with a type of SND_PCM_TYPE_ROUTE whose slave is the dmix, but the > > > route > > > pcm is returning a different value for snd_pcm_mmap_avail than the > > > dmix > > > pcm, so it is not triggering snd_pcm_wait to check for a xrun. > > > > > I think that better fix is to change the code in snd_pcm_rate_drain(). > > You > > can set avail_min to 1 there, so condition in snd_pcm_wait() will match. > > > > Does this patch help? > > > > diff -r 68d71239d651 src/pcm/pcm_rate.c > > --- a/src/pcm/pcm_rate.c Thu Sep 20 13:20:03 2007 +0200 > > +++ b/src/pcm/pcm_rate.c Fri Sep 21 10:14:41 2007 +0200 > > @@ -1076,10 +1076,10 @@ static int snd_pcm_rate_drain(snd_pcm_t > > snd_pcm_uframes_t size, ofs, saved_avail_min; > > snd_pcm_sw_params_t sw_params; > > > > - /* temporarily set avail_min to one period */ > > + /* temporarily set avail_min to one */ > > sw_params = rate->sw_params; > > saved_avail_min = sw_params.avail_min; > > - sw_params.avail_min = rate->gen.slave->period_size; > > + sw_params.avail_min = 1; > > snd_pcm_sw_params(rate->gen.slave, &sw_params); > > > > size = rate->appl_ptr - rate->last_commit_ptr; > > > > Jaroslav > > Unfortunately, I just discovered that this patch (now in alsa-lib 1.0.15-rc3) > does not always solve my problem. It does most of the time, but snd_pcm_avail > on the route occasionally returns 0, which is less than 1, so once in a while > I still get a lock-up. I can't change the 1 to a 0 in snd_pcm_drain since > snd_pcm_sw_params aborts if sw_params->avail_min == 0. > > My original approach of checking for SND_PCM_TYPE_ROUTE in snd_pcm_wait() > would still work. > > It looks as though there is a buffer to fill which is included when > snd_pcm_mmap_avail looks at the dmix pcm but not when it looks at the route in > between the rate and the dmix. I think we're looking bug on wrong place. If dmix is in XRUN state, snd_pcm_poll_descriptors_revents() should return POLLERR, thus the check for XRUN should be done in snd_pcm_wait_nocheck() after revents checking. Could you trace what occurs in your scenario in snd_pcm_wait_nocheck() ? Thanks, Jaroslav ----- Jaroslav Kysela <perex@xxxxxxx> Linux Kernel Sound Maintainer ALSA Project, SUSE Labs _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
