M64_SRC_CNTL
bus_space_write_4(sc->sc_regt, sc->sc_regh, M64_SRC_CNTL,
M64_SRC_CNTL, M64_SRC_LINE_X_LEFT_TO_RIGHT);
M64_SRC_CNTL, M64_SRC_LINE_X_RIGHT_TO_LEFT);
M64_SRC_CNTL, M64_SRC_LINE_X_LEFT_TO_RIGHT);