SNDRV_TIMER_EVENT_MSTOP
snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTOP);
(1<<SNDRV_TIMER_EVENT_MSTOP)|
if (event == SNDRV_TIMER_EVENT_MSTOP) {
loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_MSTOP, 0);
if (event == SNDRV_TIMER_EVENT_MSTOP) {