ppbus_release_bus
error = ppbus_release_bus(ppbus, self, 0, 0);
ppbus_release_bus(ppbus, dev, 0, 0);
error = ppbus_release_bus(ppbus, dev, 0, 0);
error = ppbus_release_bus(device_parent(dev), dev, how, (hz));
int ppbus_release_bus(device_t, device_t, int, unsigned int);
(void) ppbus_release_bus(sc->sc_dev, dev, PPBUS_WAIT|PPBUS_INTR, (hz));
ppbus_release_bus(sc->ppbus, sc->pps_dev.sc_dev,
ppbus_release_bus(ppbus, sc->pps_dev.sc_dev, PPBUS_WAIT, 0);