gffb_set_backlight
static void gffb_set_backlight(struct gffb_softc *, int);
gffb_set_backlight(sc, param->curval);
gffb_set_backlight(sc, sc->sc_bl_level);
gffb_set_backlight(sc, sc->sc_bl_level + 8);
gffb_set_backlight(sc, sc->sc_bl_level - 8);