PFIT_CONTROL
WARN_ON(I915_READ(PFIT_CONTROL) & PFIT_ENABLE);
I915_WRITE(PFIT_CONTROL, pipe_config->gmch_pfit.control);
I915_READ(PFIT_CONTROL));
I915_WRITE(PFIT_CONTROL, 0);
tmp = I915_READ(PFIT_CONTROL);
tmp = I915_READ(PFIT_CONTROL);
u32 pfit_control = I915_READ(PFIT_CONTROL);