[alsa-devel] pcm_prepare, and pcm_trigger
More ASoC fundamentals questions.
when doing
cat 8k8bitpcm.wav > /dev/dsp
I'm seeing neither
myplatform_pcm_prepare,
nor
myplatform_pcm_trigger
called.
Is this normal? Who calls these functions?
Thanks
On Tue, Nov 25, 2008 at 02:59:46PM +0100, John Kacur wrote:
cat 8k8bitpcm.wav > /dev/dsp
myplatform_pcm_prepare, myplatform_pcm_trigger
Is this normal? Who calls these functions?
I'd expect to see those called. They're called by the core in response to ALSA API operations - since you're using /dev/dsp the actual ALSA API client will be the OSS emulation you're using (normally the in-kernel one). For the purposes of development it's generally easier if you work with the ALSA APIs and use utilities like aplay to test. This avoids the layer of indirection added by OSS emulation, making bringup a bit clearer.
On Tue, Nov 25, 2008 at 3:48 PM, Mark Brown broonie@sirena.org.uk wrote:
On Tue, Nov 25, 2008 at 02:59:46PM +0100, John Kacur wrote:
cat 8k8bitpcm.wav > /dev/dsp
myplatform_pcm_prepare, myplatform_pcm_triggerIs this normal? Who calls these functions?
I'd expect to see those called. They're called by the core in response to ALSA API operations - since you're using /dev/dsp the actual ALSA API client will be the OSS emulation you're using (normally the in-kernel one). For the purposes of development it's generally easier if you work with the ALSA APIs and use utilities like aplay to test. This avoids the layer of indirection added by OSS emulation, making bringup a bit clearer.
Thanks again for the info.
On the embedded board I'm working on, compiling the alsa utilities isn't an option, we have the OSS emulation as a requirement.
On Tue, Nov 25, 2008 at 03:50:21PM +0100, John Kacur wrote:
On the embedded board I'm working on, compiling the alsa utilities isn't an option, we have the OSS emulation as a requirement.
That's sadly not uncommon for actual deployment but normally during development it's possible to install the ALSA utilities to make that process easier, even if they don't appear on production systems.
participants (2)
-
John Kacur -
Mark Brown