On Apr 4 2017 14:57, Kuninori Morimoto wrote:
Ctrl-Z case
- aplay xxx.wav
=> - hw_param
- SNDRV_PCM_TRIGGER_START
- Ctrl-Z
- SNDRV_PCM_TRIGGER_STOP
- fg
=> - ## no hw_param here
- SNDRV_PCM_TRIGGER_START
- Ctrl-C (stop)
- SNDRV_PCM_TRIGGER_STOP
No issues.
I think it better to implement what you want in any .prepare
callbacks, instead of the .be_hw_params_fixup callback, because in
this case, PCM substream lapses into XRUN state in call graph from
your hw IRQ handler. Typical applications recover from this state by
calling ioctl(PREPARE), without any call of ioctl(HW_PARAMS).
Actually, you can see applications call ioctl(PREPARE), before you see
call of 'struct snd_pcm_ops.trigger(START)'.
Hmm...
Above .be_hw_params_fixup is used to convert sampling rate or channel
number or some other related things between SoC / Codec as DPCM feature.
Thus, I can't switch to .be_hw_params_fixup to .prepare I guess.
But Mark, am I misunderstanding ?
In 'struct snd_pcm_ops.prepare' callback, configured parameters of PCM
substream are available via members of 'struct snd_pcm_runtime'. The
runtime is a member of 'struct snd_pcm_substream'. It's available in any
of .prepare callbacks in ALSA SoC part.
Regards
Takashi Sakamoto
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