[alsa-devel] my driver can't reproduce continuously

[Kuninori Morimoto]

Hi

Now I'm creating sound driver.
But can't reproduce continuously.
So, I would like to ask.

I use module of SH to play sound.
Player is aplay, sound data is wav file.

Q1)
When I play sound, aplay said

underrun!!! (at least 0.000 ms long)
underrun!!! (at least 0.000 ms long)
underrun!!! (at least 0.000 ms long)
underrun!!! (at least 0.000 ms long)

I checked source of aplay,
but can not understand about snd_pcm_status_get_state.
why snd_pcm_status_get_state return SND_PCM_STATE_XRUN ?
What should my driver do (or where should I check) ?

Q2)
The reason that it can not reproduce continuously
seems soc-core.c :: soc_pcm_trigger timing.
Call timing of soc_pcm_trigger is slow.
What should my driver do to make call timing more fast ?

Best regards
--
Kuninori Morimoto