pcm_chn_create
ch = pcm_chn_create(d, NULL, cls, dir, -1, devinfo);
struct pcm_channel *pcm_chn_create(struct snddev_info *d, struct pcm_channel *parent, kobj_class_t cls, int dir, int num, void *devinfo);
ch = pcm_chn_create(d, parent, &vchan_class, direction, num, parent);