RTW_F_DK_VALID
sc->sc_flags &= ~RTW_F_DK_VALID;
sc->sc_flags &= ~RTW_F_DK_VALID;
sc->sc_flags &= ~RTW_F_DK_VALID;
sc->sc_flags &= ~RTW_F_DK_VALID;
if ((sc->sc_flags & RTW_F_DK_VALID) != 0 ||
sc->sc_flags |= RTW_F_DK_VALID;
sc->sc_flags &= ~RTW_F_DK_VALID;