drm/i915: extract intel_set_config_compute_mode_changes

This computes what exactly changed in the modeset configuration, i.e.
whether a full modeset is required or only an update of the
framebuffer base address or no change at all.

In the future we might add more checks for e.g. when only the output
mode changed, so that we could do a minimal modeset for outputs that
support this. Like the lvds/eDP panels where we only need to update
the panel fitter.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -6805,14 +6805,46 @@ static void intel_set_config_restore_state(struct drm_device *dev,
 	}
 }
 
+static void
+intel_set_config_compute_mode_changes(struct drm_mode_set *set,
+				      struct intel_set_config *config)
+{
+
+	/* We should be able to check here if the fb has the same properties
+	 * and then just flip_or_move it */
+	if (set->crtc->fb != set->fb) {
+		/* If we have no fb then treat it as a full mode set */
+		if (set->crtc->fb == NULL) {
+			DRM_DEBUG_KMS("crtc has no fb, full mode set\n");
+			config->mode_changed = true;
+		} else if (set->fb == NULL) {
+			config->mode_changed = true;
+		} else if (set->fb->depth != set->crtc->fb->depth) {
+			config->mode_changed = true;
+		} else if (set->fb->bits_per_pixel !=
+			   set->crtc->fb->bits_per_pixel) {
+			config->mode_changed = true;
+		} else
+			config->fb_changed = true;
+	}
+
+	if (set->x != set->crtc->x || set->y != set->crtc->y)
+		config->fb_changed = true;
+
+	if (set->mode && !drm_mode_equal(set->mode, &set->crtc->mode)) {
+		DRM_DEBUG_KMS("modes are different, full mode set\n");
+		drm_mode_debug_printmodeline(&set->crtc->mode);
+		drm_mode_debug_printmodeline(set->mode);
+		config->mode_changed = true;
+	}
+}
+
 static int intel_crtc_set_config(struct drm_mode_set *set)
 {
 	struct drm_device *dev;
 	struct drm_crtc *new_crtc;
 	struct drm_encoder *new_encoder;
 	struct drm_framebuffer *old_fb = NULL;
-	bool mode_changed = false; /* if true do a full mode set */
-	bool fb_changed = false; /* if true and !mode_changed just do a flip */
 	struct drm_connector *connector;
 	int count = 0, ro;
 	struct drm_mode_set save_set;
@@ -6860,33 +6892,11 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 	save_set.y = set->crtc->y;
 	save_set.fb = set->crtc->fb;
 
-	/* We should be able to check here if the fb has the same properties
-	 * and then just flip_or_move it */
-	if (set->crtc->fb != set->fb) {
-		/* If we have no fb then treat it as a full mode set */
-		if (set->crtc->fb == NULL) {
-			DRM_DEBUG_KMS("crtc has no fb, full mode set\n");
-			mode_changed = true;
-		} else if (set->fb == NULL) {
-			mode_changed = true;
-		} else if (set->fb->depth != set->crtc->fb->depth) {
-			mode_changed = true;
-		} else if (set->fb->bits_per_pixel !=
-			   set->crtc->fb->bits_per_pixel) {
-			mode_changed = true;
-		} else
-			fb_changed = true;
-	}
-
-	if (set->x != set->crtc->x || set->y != set->crtc->y)
-		fb_changed = true;
-
-	if (set->mode && !drm_mode_equal(set->mode, &set->crtc->mode)) {
-		DRM_DEBUG_KMS("modes are different, full mode set\n");
-		drm_mode_debug_printmodeline(&set->crtc->mode);
-		drm_mode_debug_printmodeline(set->mode);
-		mode_changed = true;
-	}
+	/* Compute whether we need a full modeset, only an fb base update or no
+	 * change at all. In the future we might also check whether only the
+	 * mode changed, e.g. for LVDS where we only change the panel fitter in
+	 * such cases. */
+	intel_set_config_compute_mode_changes(set, config);
 
 	/* a) traverse passed in connector list and get encoders for them */
 	count = 0;
@@ -6902,7 +6912,7 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 
 		if (new_encoder != connector->encoder) {
 			DRM_DEBUG_KMS("encoder changed, full mode switch\n");
-			mode_changed = true;
+			config->mode_changed = true;
 			/* If the encoder is reused for another connector, then
 			 * the appropriate crtc will be set later.
 			 */
@@ -6930,12 +6940,11 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 		/* Make sure the new CRTC will work with the encoder */
 		if (new_crtc &&
 		    !intel_encoder_crtc_ok(connector->encoder, new_crtc)) {
-			ret = -EINVAL;
-			goto fail;
+			return -EINVAL;
 		}
 		if (new_crtc != connector->encoder->crtc) {
 			DRM_DEBUG_KMS("crtc changed, full mode switch\n");
-			mode_changed = true;
+			config->mode_changed = true;
 			connector->encoder->crtc = new_crtc;
 		}
 		if (new_crtc) {
@@ -6948,7 +6957,7 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 		}
 	}
 
-	if (mode_changed) {
+	if (config->mode_changed) {
 		set->crtc->enabled = drm_helper_crtc_in_use(set->crtc);
 		if (set->crtc->enabled) {
 			DRM_DEBUG_KMS("attempting to set mode from"
@@ -6972,7 +6981,7 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 			}
 		}
 		drm_helper_disable_unused_functions(dev);
-	} else if (fb_changed) {
+	} else if (config->fb_changed) {
 		set->crtc->x = set->x;
 		set->crtc->y = set->y;
 
@@ -6995,7 +7004,7 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 	intel_set_config_restore_state(dev, config);
 
 	/* Try to restore the config */
-	if (mode_changed &&
+	if (config->mode_changed &&
 	    !intel_set_mode(save_set.crtc, save_set.mode,
 			    save_set.x, save_set.y, save_set.fb))
 		DRM_ERROR("failed to restore config after modeset failure\n");

drivers/gpu/drm/i915/intel_drv.h

@@ -427,6 +427,9 @@ struct intel_set_config {
 	struct drm_connector *save_connectors;
 	struct drm_encoder *save_encoders;
 	struct drm_crtc *save_crtcs;
+
+	bool fb_changed;
+	bool mode_changed;
 };
 
 extern bool intel_set_mode(struct drm_crtc *crtc, struct drm_display_mode *mode,