snd_pcm_playback_silence
snd_pcm_playback_silence(substream, new_hw_ptr);
void snd_pcm_playback_silence(struct snd_pcm_substream *substream,
snd_pcm_playback_silence(substream, ULONG_MAX);
snd_pcm_playback_silence(substream, ULONG_MAX);
snd_pcm_playback_silence(substream, ULONG_MAX);