drm/i915: Kill most of the FBC register save/restore

We will anyway re-enable FBC normally after resume, so trying to save
and restore the register makes little sense.

We do need to preserve the FBC1 interval bits in FBC_CONTROL since
we only initialize them during driver load, and try to preserve them
after that.

v2: s/I915_HAS_FBC/HAS_FBC/ and fix the check for gen4
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -859,11 +859,7 @@ struct i915_suspend_saved_registers {
 	u32 savePFIT_CONTROL;
 	u32 save_palette_a[256];
 	u32 save_palette_b[256];
-	u32 saveDPFC_CB_BASE;
-	u32 saveFBC_CFB_BASE;
-	u32 saveFBC_LL_BASE;
 	u32 saveFBC_CONTROL;
-	u32 saveFBC_CONTROL2;
 	u32 saveIER;
 	u32 saveIIR;
 	u32 saveIMR;

drivers/gpu/drm/i915/i915_suspend.c

@@ -236,19 +236,9 @@ static void i915_save_display(struct drm_device *dev)
 		dev_priv->regfile.savePP_DIVISOR = I915_READ(PP_DIVISOR);
 	}
 
-	/* Only regfile.save FBC state on the platform that supports FBC */
-	if (HAS_FBC(dev)) {
-		if (HAS_PCH_SPLIT(dev)) {
-			dev_priv->regfile.saveDPFC_CB_BASE = I915_READ(ILK_DPFC_CB_BASE);
-		} else if (IS_GM45(dev)) {
-			dev_priv->regfile.saveDPFC_CB_BASE = I915_READ(DPFC_CB_BASE);
-		} else {
-			dev_priv->regfile.saveFBC_CFB_BASE = I915_READ(FBC_CFB_BASE);
-			dev_priv->regfile.saveFBC_LL_BASE = I915_READ(FBC_LL_BASE);
-			dev_priv->regfile.saveFBC_CONTROL2 = I915_READ(FBC_CONTROL2);
-			dev_priv->regfile.saveFBC_CONTROL = I915_READ(FBC_CONTROL);
-		}
-	}
+	/* save FBC interval */
+	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
+		dev_priv->regfile.saveFBC_CONTROL = I915_READ(FBC_CONTROL);
 
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		i915_save_vga(dev);
@@ -300,18 +290,10 @@ static void i915_restore_display(struct drm_device *dev)
 
 	/* only restore FBC info on the platform that supports FBC*/
 	intel_disable_fbc(dev);
-	if (HAS_FBC(dev)) {
-		if (HAS_PCH_SPLIT(dev)) {
-			I915_WRITE(ILK_DPFC_CB_BASE, dev_priv->regfile.saveDPFC_CB_BASE);
-		} else if (IS_GM45(dev)) {
-			I915_WRITE(DPFC_CB_BASE, dev_priv->regfile.saveDPFC_CB_BASE);
-		} else {
-			I915_WRITE(FBC_CFB_BASE, dev_priv->regfile.saveFBC_CFB_BASE);
-			I915_WRITE(FBC_LL_BASE, dev_priv->regfile.saveFBC_LL_BASE);
-			I915_WRITE(FBC_CONTROL2, dev_priv->regfile.saveFBC_CONTROL2);
-			I915_WRITE(FBC_CONTROL, dev_priv->regfile.saveFBC_CONTROL);
-		}
-	}
+
+	/* restore FBC interval */
+	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
+		I915_WRITE(FBC_CONTROL, dev_priv->regfile.saveFBC_CONTROL);
 
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		i915_restore_vga(dev);