[alsa-devel] Will ALSA ever call _prepare or _hw_params while it's playing?

Clemens Ladisch clemens at alsa-project.org
Wed May 21 17:53:38 CEST 2008

Timur Tabi wrote:
> I have an ASoC driver with a _hw_params, _prepare, and _trigger functions.  I've
> recently discovered that I need to keep one of my devices disabled until
> playback starts.
> So I would like to know if ALSA will ever call _hw_params, _prepare, or _trigger
> if playback or capture is currently in process, or will ALSA first call the
> _trigger to stop/pause the driver.

While a stream is running (after trigger with START), ALSA will only
call the pointer or the trigger (STOP/PAUSE/SUSPEND) callbacks.

Different streams are not synchronized in any way.  (This also applies to
the playback/capture streams of one card.)


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