chn_trigger
chn_trigger(c, PCMTRIG_ABORT);
chn_trigger(c, PCMTRIG_EMLDMAWR);
chn_trigger(c, PCMTRIG_EMLDMARD);
err = chn_trigger(c, PCMTRIG_START);
chn_trigger(c, PCMTRIG_ABORT);
chn_trigger(c, PCMTRIG_ABORT);
int chn_trigger(struct pcm_channel *c, int go);