VLV_BLC_PWM_CTL
ctl = I915_READ(VLV_BLC_PWM_CTL(pipe));
return I915_READ(VLV_BLC_PWM_CTL(pipe)) & BACKLIGHT_DUTY_CYCLE_MASK;
tmp = I915_READ(VLV_BLC_PWM_CTL(pipe)) & ~BACKLIGHT_DUTY_CYCLE_MASK;
I915_WRITE(VLV_BLC_PWM_CTL(pipe), tmp | level);
I915_WRITE(VLV_BLC_PWM_CTL(pipe), ctl);