VR_ISR
status = CSR_READ_2(sc, VR_ISR);
CSR_WRITE_2(sc, VR_ISR, status);
status = CSR_READ_2(sc, VR_ISR);
status = CSR_READ_2(sc, VR_ISR);
CSR_WRITE_2(sc, VR_ISR, status);
CSR_WRITE_2(sc, VR_ISR, status);
status = CSR_READ_2(sc, VR_ISR);
CSR_WRITE_2(sc, VR_ISR, 0xFFFF);
CSR_WRITE_2(sc, VR_ISR, 0xFFFF);
CSR_WRITE_2(sc, VR_ISR, 0xFFFF);