update the pcm status for the next period
void snd_pcm_period_elapsed (
|struct snd_pcm_substream * substream|
the pcm substream instance
This function is called from the interrupt handler when the
PCM has processed the period size. It will update the current
pointer, wake up sleepers, etc.
Even if more than one periods have elapsed since the last call, you
have to call this only once.