[alsa-devel] External samplerate changes, UAC2 clock topologies

Daniel Mack daniel at caiaq.de
Wed Jun 9 13:30:00 CEST 2010

On Wed, Jun 09, 2010 at 11:16:28AM +0200, Daniel Mack wrote:
> On Fri, Jun 04, 2010 at 09:49:36PM +0200, Jaroslav Kysela wrote:
> > If a stream parameter changes, the driver should interrupt streaming
> > immediatelly. The check should be in the trigger() callback (-EIO
> > error code) and if the stream is already running - it should be put
> > to the
> > SNDRV_PCM_STATE_DRAINING (capture) to let the application obtain the
> > captured samples until the parameter change. Just call
> > snd_pcm_stop() with the new state for the substream. For playback,
> > the stream should be put to the SNDRV_PCM_STATE_OPEN state to wait
> > to settle new parameters from an application (it means that all I/O
> > ops will return -EBADFD).
> Hmm. I implemented this now, but at least aplay won't stop when this
> code path is triggered. Is there anything else I should do, except for
> calling snd_pcm_stop()?

Strange enough, aplay doesn't even quit when the device is unplugged.
Can anyone confirm this with an UAC1 device?


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