mmBIF_DOORBELL_INT_CNTL
reg = RREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL);
WREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL, reg_data);
bif_doorbell_intr_cntl = RREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL);
WREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL, bif_doorbell_intr_cntl);
bif_doorbell_intr_cntl = RREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL);
WREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL, bif_doorbell_intr_cntl);