PFIT_PGM_RATIOS
I915_WRITE(PFIT_PGM_RATIOS, pipe_config->gmch_pfit.pgm_ratios);
pipe_config->gmch_pfit.pgm_ratios = I915_READ(PFIT_PGM_RATIOS);
ratio = I915_READ(PFIT_PGM_RATIOS) >> PFIT_VERT_SCALE_SHIFT_965;
ratio = I915_READ(PFIT_PGM_RATIOS);