output: make wlr_output_enable return a bool

backend/drm/drm.c

@@ -342,17 +342,17 @@ static void drm_connector_start_renderer(struct wlr_drm_connector *conn) {
 	}
 }
 
-void enable_drm_connector(struct wlr_output *output, bool enable) {
+bool enable_drm_connector(struct wlr_output *output, bool enable) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
 	if (conn->state != WLR_DRM_CONN_CONNECTED
 			&& conn->state != WLR_DRM_CONN_NEEDS_MODESET) {
-		return;
+		return false;
 	}
 
 	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)output->backend;
 	bool ok = drm->iface->conn_enable(drm, conn, enable);
 	if (!ok) {
-		return;
+		return false;
 	}
 
 	if (enable) {
@@ -360,6 +360,7 @@ void enable_drm_connector(struct wlr_output *output, bool enable) {
 	}
 
 	wlr_output_update_enabled(&conn->output, enable);
+	return true;
 }
 
 static void realloc_planes(struct wlr_drm_backend *drm, const uint32_t *crtc_in,

include/backend/drm/drm.h

@@ -143,6 +143,6 @@ void finish_drm_resources(struct wlr_drm_backend *drm);
 void restore_drm_outputs(struct wlr_drm_backend *drm);
 void scan_drm_connectors(struct wlr_drm_backend *state);
 int handle_drm_event(int fd, uint32_t mask, void *data);
-void enable_drm_connector(struct wlr_output *output, bool enable);
+bool enable_drm_connector(struct wlr_output *output, bool enable);
 
 #endif

include/wlr/interfaces/wlr_output.h

@@ -15,7 +15,7 @@
 #include <wlr/types/wlr_output.h>
 
 struct wlr_output_impl {
-	void (*enable)(struct wlr_output *output, bool enable);
+	bool (*enable)(struct wlr_output *output, bool enable);
 	bool (*set_mode)(struct wlr_output *output, struct wlr_output_mode *mode);
 	bool (*set_custom_mode)(struct wlr_output *output, int32_t width,
 		int32_t height, int32_t refresh);

include/wlr/types/wlr_output.h

@@ -124,11 +124,15 @@ struct wlr_output_event_swap_buffers {
 
 struct wlr_surface;
 
-void wlr_output_enable(struct wlr_output *output, bool enable);
+/**
+ * Enables or disables the output. A disabled output is turned off and doesn't
+ * emit `frame` events.
+ */
+bool wlr_output_enable(struct wlr_output *output, bool enable);
 void wlr_output_create_global(struct wlr_output *output);
 void wlr_output_destroy_global(struct wlr_output *output);
 /**
- * Sets the output mode.
+ * Sets the output mode. Enables the output if it's currently disabled.
  */
 bool wlr_output_set_mode(struct wlr_output *output,
 	struct wlr_output_mode *mode);

types/wlr_output.c

@@ -142,14 +142,15 @@ static void output_update_matrix(struct wlr_output *output) {
 		output->height, output->transform);
 }
 
-void wlr_output_enable(struct wlr_output *output, bool enable) {
+bool wlr_output_enable(struct wlr_output *output, bool enable) {
 	if (output->enabled == enable) {
-		return;
+		return true;
 	}
 
 	if (output->impl->enable) {
-		output->impl->enable(output, enable);
+		return output->impl->enable(output, enable);
 	}
+	return false;
 }
 
 bool wlr_output_set_mode(struct wlr_output *output,