PRCM_AM335X_DISP_CLKSEL
oreg = bus_space_read_4(sc->sc_iot, sc->sc_prcm, PRCM_AM335X_DISP_CLKSEL);
bus_space_write_4(sc->sc_iot, sc->sc_prcm, PRCM_AM335X_DISP_CLKSEL, oreg);
oreg = bus_space_read_4(sc->sc_iot, sc->sc_prcm, PRCM_AM335X_DISP_CLKSEL);
bus_space_write_4(sc->sc_iot, sc->sc_prcm, PRCM_AM335X_DISP_CLKSEL, oreg);