static int snd_pcm_do_stop(struct snd_pcm_substream *substream,
			   snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream &&
	    snd_pcm_running(substream)) {
		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
		substream->runtime->stop_operating = true;
	}
	return 0; /* unconditionally stop all substreams */
}
static int snd_pcm_do_stop(struct snd_pcm_substream *substream,
			   snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream &&
	    snd_pcm_running(substream)) {
		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
		substream->runtime->stop_operating = true;
	}
	return 0;  
}