call_vop
num = call_vop(inst, get_debug_info, str, sizeof(str), i++);
return call_vop(inst, check_ready, type);
return call_vop(inst, process_output, &vbuf->vb2_buf);
return call_vop(inst, process_capture, &vbuf->vb2_buf);
ret = call_vop(inst, start, q->type);
ret = call_vop(inst, ctrl_init);