drm/i915: Disable crtcs gracefully before GPU reset on gen3/4

The GPU reset also resets the display on gen3/4. The g33 docs say we
should disable all planes before flipping the reset switch. Just
disable all the crtcs instead. That seems a nicer thing to do anyway.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2803,6 +2803,9 @@ static void intel_update_primary_planes(struct drm_device *dev)
 
 void intel_prepare_reset(struct drm_device *dev)
 {
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_crtc *crtc;
+
 	/* no reset support for gen2 */
 	if (IS_GEN2(dev))
 		return;
@@ -2812,6 +2815,15 @@ void intel_prepare_reset(struct drm_device *dev)
 		return;
 
 	drm_modeset_lock_all(dev);
+
+	/*
+	 * Disabling the crtcs gracefully seems nicer. Also the
+	 * g33 docs say we should at least disable all the planes.
+	 */
+	for_each_intel_crtc(dev, crtc) {
+		if (crtc->active)
+			dev_priv->display.crtc_disable(&crtc->base);
+	}
 }
 
 void intel_finish_reset(struct drm_device *dev)

drivers/gpu/drm/i915/intel_uncore.c

@@ -1371,8 +1371,6 @@ static int g4x_reset_complete(struct drm_device *dev)
 
 static int g33_do_reset(struct drm_device *dev)
 {
-	/* FIXME spec says to turn off all planes and wait 1 usec before reset */
-
 	pci_write_config_byte(dev->pdev, I915_GDRST, GRDOM_RESET_ENABLE);
 	return wait_for(g4x_reset_complete(dev), 500);
 }