chn_setparam
r = chn_setparam(c, fmt, spd);
ret = chn_setparam(c, format, speed);
chn_setparam(c, c->format, oldspeed);
ret = chn_setparam(c, format, speed);
chn_setparam(c, oldformat, oldspeed);
int chn_setparam(struct pcm_channel *c, uint32_t format, uint32_t speed);