drm/atomic: add drm_atomic_get_existing_*_state helpers

There are cases where we want to test if a given object is
part of the state, but don't want to add them if they're not.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_atomic.c

@@ -203,13 +203,12 @@ struct drm_crtc_state *
 drm_atomic_get_crtc_state(struct drm_atomic_state *state,
 			  struct drm_crtc *crtc)
 {
-	int ret, index;
+	int ret, index = drm_crtc_index(crtc);
 	struct drm_crtc_state *crtc_state;
 
-	index = drm_crtc_index(crtc);
-
-	if (state->crtc_states[index])
-		return state->crtc_states[index];
+	crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);
+	if (crtc_state)
+		return crtc_state;
 
 	ret = drm_modeset_lock(&crtc->mutex, state->acquire_ctx);
 	if (ret)
@@ -337,13 +336,12 @@ struct drm_plane_state *
 drm_atomic_get_plane_state(struct drm_atomic_state *state,
 			  struct drm_plane *plane)
 {
-	int ret, index;
+	int ret, index = drm_plane_index(plane);
 	struct drm_plane_state *plane_state;
 
-	index = drm_plane_index(plane);
-
-	if (state->plane_states[index])
-		return state->plane_states[index];
+	plane_state = drm_atomic_get_existing_plane_state(state, plane);
+	if (plane_state)
+		return plane_state;
 
 	ret = drm_modeset_lock(&plane->mutex, state->acquire_ctx);
 	if (ret)

include/drm/drm_atomic.h

@@ -54,6 +54,56 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
 		struct drm_connector_state *state, struct drm_property *property,
 		uint64_t val);
 
+/**
+ * drm_atomic_get_existing_crtc_state - get crtc state, if it exists
+ * @state: global atomic state object
+ * @crtc: crtc to grab
+ *
+ * This function returns the crtc state for the given crtc, or NULL
+ * if the crtc is not part of the global atomic state.
+ */
+static inline struct drm_crtc_state *
+drm_atomic_get_existing_crtc_state(struct drm_atomic_state *state,
+				   struct drm_crtc *crtc)
+{
+	return state->crtc_states[drm_crtc_index(crtc)];
+}
+
+/**
+ * drm_atomic_get_existing_plane_state - get plane state, if it exists
+ * @state: global atomic state object
+ * @plane: plane to grab
+ *
+ * This function returns the plane state for the given plane, or NULL
+ * if the plane is not part of the global atomic state.
+ */
+static inline struct drm_plane_state *
+drm_atomic_get_existing_plane_state(struct drm_atomic_state *state,
+				    struct drm_plane *plane)
+{
+	return state->plane_states[drm_plane_index(plane)];
+}
+
+/**
+ * drm_atomic_get_existing_connector_state - get connector state, if it exists
+ * @state: global atomic state object
+ * @connector: connector to grab
+ *
+ * This function returns the connector state for the given connector,
+ * or NULL if the connector is not part of the global atomic state.
+ */
+static inline struct drm_connector_state *
+drm_atomic_get_existing_connector_state(struct drm_atomic_state *state,
+					struct drm_connector *connector)
+{
+	int index = drm_connector_index(connector);
+
+	if (index >= state->num_connector)
+		return NULL;
+
+	return state->connector_states[index];
+}
+
 int __must_check
 drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
 			      struct drm_crtc *crtc);