BLC_PWM_CTL2
ctl2 = I915_READ(BLC_PWM_CTL2);
tmp = I915_READ(BLC_PWM_CTL2);
I915_WRITE(BLC_PWM_CTL2, tmp & ~BLM_PWM_ENABLE);
ctl2 = I915_READ(BLC_PWM_CTL2);
I915_WRITE(BLC_PWM_CTL2, ctl2);
I915_WRITE(BLC_PWM_CTL2, ctl2);
POSTING_READ(BLC_PWM_CTL2);
I915_WRITE(BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE);