SNDRV_PCM_IOCTL_PREPARE
result = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_PREPARE, NULL);
SNDRV_PCM_IOCTL_PREPARE, NULL);
err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_PREPARE, NULL);
case SNDRV_PCM_IOCTL_PREPARE:
case SNDRV_PCM_IOCTL_PREPARE:
case SNDRV_PCM_IOCTL_PREPARE: