drm/i915: don't save/restore panel fitter registers

AFAICT i9xx_pfit_disable() on the GMCH display crtc disable path in
i9xx_crtc_disable() will always disable the panel fitter by writing 0 to
PFIT_CONTROL. The register save will always save/restore 0. Also we
completely recompue both in intel_gmch_panel_fitting so there's no way
we depend upon leftover bits.

Move the PFIT_CONTROL and PFIT_PGM_RATIOS save/restore to UMS
code. While at it, save/restore them both under the same conditions.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
[danvet: Make it a bit clearer that we nowhere depend upon these
bits.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_suspend.c

@@ -208,23 +208,17 @@ static void i915_save_display(struct drm_device *dev)
 		if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev))
 			dev_priv->regfile.saveLVDS = I915_READ(PCH_LVDS);
 	} else if (IS_VALLEYVIEW(dev)) {
-		dev_priv->regfile.savePFIT_PGM_RATIOS = I915_READ(PFIT_PGM_RATIOS);
-
 		dev_priv->regfile.saveBLC_HIST_CTL =
 			I915_READ(VLV_BLC_HIST_CTL(PIPE_A));
 		dev_priv->regfile.saveBLC_HIST_CTL_B =
 			I915_READ(VLV_BLC_HIST_CTL(PIPE_B));
 	} else {
 		dev_priv->regfile.savePP_CONTROL = I915_READ(PP_CONTROL);
-		dev_priv->regfile.savePFIT_PGM_RATIOS = I915_READ(PFIT_PGM_RATIOS);
 		dev_priv->regfile.saveBLC_HIST_CTL = I915_READ(BLC_HIST_CTL);
 		if (IS_MOBILE(dev) && !IS_I830(dev))
 			dev_priv->regfile.saveLVDS = I915_READ(LVDS);
 	}
 
-	if (!IS_I830(dev) && !IS_845G(dev) && !HAS_PCH_SPLIT(dev))
-		dev_priv->regfile.savePFIT_CONTROL = I915_READ(PFIT_CONTROL);
-
 	if (HAS_PCH_SPLIT(dev)) {
 		dev_priv->regfile.savePP_ON_DELAYS = I915_READ(PCH_PP_ON_DELAYS);
 		dev_priv->regfile.savePP_OFF_DELAYS = I915_READ(PCH_PP_OFF_DELAYS);
@@ -263,9 +257,6 @@ static void i915_restore_display(struct drm_device *dev)
 	else if (INTEL_INFO(dev)->gen <= 4 && IS_MOBILE(dev) && !IS_I830(dev))
 		I915_WRITE(LVDS, dev_priv->regfile.saveLVDS & mask);
 
-	if (!IS_I830(dev) && !IS_845G(dev) && !HAS_PCH_SPLIT(dev))
-		I915_WRITE(PFIT_CONTROL, dev_priv->regfile.savePFIT_CONTROL);
-
 	if (HAS_PCH_SPLIT(dev)) {
 		I915_WRITE(PCH_PP_ON_DELAYS, dev_priv->regfile.savePP_ON_DELAYS);
 		I915_WRITE(PCH_PP_OFF_DELAYS, dev_priv->regfile.savePP_OFF_DELAYS);
@@ -277,7 +268,6 @@ static void i915_restore_display(struct drm_device *dev)
 		I915_WRITE(VLV_BLC_HIST_CTL(PIPE_B),
 			   dev_priv->regfile.saveBLC_HIST_CTL);
 	} else {
-		I915_WRITE(PFIT_PGM_RATIOS, dev_priv->regfile.savePFIT_PGM_RATIOS);
 		I915_WRITE(BLC_HIST_CTL, dev_priv->regfile.saveBLC_HIST_CTL);
 		I915_WRITE(PP_ON_DELAYS, dev_priv->regfile.savePP_ON_DELAYS);
 		I915_WRITE(PP_OFF_DELAYS, dev_priv->regfile.savePP_OFF_DELAYS);

drivers/gpu/drm/i915/i915_ums.c

@@ -270,6 +270,12 @@ void i915_save_display_reg(struct drm_device *dev)
 	}
 	/* FIXME: regfile.save TV & SDVO state */
 
+	/* Panel fitter */
+	if (!IS_I830(dev) && !IS_845G(dev) && !HAS_PCH_SPLIT(dev)) {
+		dev_priv->regfile.savePFIT_CONTROL = I915_READ(PFIT_CONTROL);
+		dev_priv->regfile.savePFIT_PGM_RATIOS = I915_READ(PFIT_PGM_RATIOS);
+	}
+
 	/* Backlight */
 	if (INTEL_INFO(dev)->gen <= 4)
 		pci_read_config_byte(dev->pdev, PCI_LBPC,
@@ -315,6 +321,12 @@ void i915_restore_display_reg(struct drm_device *dev)
 		I915_WRITE(BLC_PWM_CTL, dev_priv->regfile.saveBLC_PWM_CTL);
 	}
 
+	/* Panel fitter */
+	if (!IS_I830(dev) && !IS_845G(dev) && !HAS_PCH_SPLIT(dev)) {
+		I915_WRITE(PFIT_PGM_RATIOS, dev_priv->regfile.savePFIT_PGM_RATIOS);
+		I915_WRITE(PFIT_CONTROL, dev_priv->regfile.savePFIT_CONTROL);
+	}
+
 	/* Display port ratios (must be done before clock is set) */
 	if (SUPPORTS_INTEGRATED_DP(dev)) {
 		I915_WRITE(_PIPEA_DATA_M_G4X, dev_priv->regfile.savePIPEA_GMCH_DATA_M);