backend/drm: stop initializing renderer for parent backend

Unless we're dealing with a multi-GPU setup and the backend being
initialized is secondary, we don't need a renderer nor an allocator.
Stop initializing these.

backend/drm/backend.c

@@ -53,8 +53,13 @@ static void backend_destroy(struct wlr_backend *backend) {
 	wl_list_remove(&drm->dev_change.link);
 	wl_list_remove(&drm->dev_remove.link);
 
+	gbm_device_destroy(drm->gbm);
+
+	if (drm->parent) {
+		finish_drm_renderer(&drm->mgpu_renderer);
+	}
+
 	finish_drm_resources(drm);
-	finish_drm_renderer(&drm->renderer);
 
 	free(drm->name);
 	wlr_session_close_file(drm->session, drm->dev);
@@ -219,8 +224,9 @@ struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 		goto error_event;
 	}
 
-	if (!init_drm_renderer(drm, &drm->renderer)) {
+	drm->gbm = gbm_create_device(drm->fd);
-		wlr_log(WLR_ERROR, "Failed to initialize renderer");
+	if (!drm->gbm) {
+		wlr_log(WLR_ERROR, "Failed to create GBM device");
 		goto error_event;
 	}
 
@@ -229,9 +235,14 @@ struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 		drm->backend.renderer = wlr_backend_get_renderer(&drm->parent->backend);
 		assert(drm->backend.renderer != NULL);
 
+		if (!init_drm_renderer(drm, &drm->mgpu_renderer)) {
+			wlr_log(WLR_ERROR, "Failed to initialize renderer");
+			goto error_event;
+		}
+
 		// We'll perform a multi-GPU copy for all submitted buffers, we need
 		// to be able to texture from them
-		struct wlr_renderer *renderer = drm->renderer.wlr_rend;
+		struct wlr_renderer *renderer = drm->mgpu_renderer.wlr_rend;
 		const struct wlr_drm_format_set *texture_formats =
 			wlr_renderer_get_dmabuf_texture_formats(renderer);
 		if (texture_formats == NULL) {

backend/drm/drm.c

@@ -401,14 +401,14 @@ static bool drm_connector_set_pending_fb(struct wlr_drm_connector *conn,
 	struct wlr_buffer *local_buf;
 	if (drm->parent) {
 		struct wlr_drm_format *format =
-			drm_plane_pick_render_format(plane, &drm->renderer);
+			drm_plane_pick_render_format(plane, &drm->mgpu_renderer);
 		if (format == NULL) {
 			wlr_log(WLR_ERROR, "Failed to pick primary plane format");
 			return false;
 		}
 
 		// TODO: fallback to modifier-less buffer allocation
-		bool ok = init_drm_surface(&plane->mgpu_surf, &drm->renderer,
+		bool ok = init_drm_surface(&plane->mgpu_surf, &drm->mgpu_renderer,
 			state->buffer->width, state->buffer->height, format);
 		free(format);
 		if (!ok) {
@@ -632,14 +632,14 @@ static bool drm_connector_init_renderer(struct wlr_drm_connector *conn,
 		int height = mode.vdisplay;
 
 		struct wlr_drm_format *format =
-			drm_plane_pick_render_format(plane, &drm->renderer);
+			drm_plane_pick_render_format(plane, &drm->mgpu_renderer);
 		if (format == NULL) {
 			wlr_log(WLR_ERROR, "Failed to pick primary plane format");
 			return false;
 		}
 
 		// TODO: fallback to modifier-less buffer allocation
-		bool ok = init_drm_surface(&plane->mgpu_surf, &drm->renderer,
+		bool ok = init_drm_surface(&plane->mgpu_surf, &drm->mgpu_renderer,
 			width, height, format);
 		free(format);
 		if (!ok) {
@@ -834,13 +834,13 @@ static bool drm_connector_set_cursor(struct wlr_output *output,
 		struct wlr_buffer *local_buf;
 		if (drm->parent) {
 			struct wlr_drm_format *format =
-				drm_plane_pick_render_format(plane, &drm->renderer);
+				drm_plane_pick_render_format(plane, &drm->mgpu_renderer);
 			if (format == NULL) {
 				wlr_log(WLR_ERROR, "Failed to pick cursor plane format");
 				return false;
 			}
 
-			bool ok = init_drm_surface(&plane->mgpu_surf, &drm->renderer,
+			bool ok = init_drm_surface(&plane->mgpu_surf, &drm->mgpu_renderer,
 				buffer->width, buffer->height, format);
 			free(format);
 			if (!ok) {

backend/drm/renderer.c

@@ -23,32 +23,21 @@ bool init_drm_renderer(struct wlr_drm_backend *drm,
 		struct wlr_drm_renderer *renderer) {
 	renderer->backend = drm;
 
-	renderer->gbm = gbm_create_device(drm->fd);
-	if (!renderer->gbm) {
-		wlr_log(WLR_ERROR, "Failed to create GBM device");
-		return false;
-	}
-
 	renderer->wlr_rend = renderer_autocreate_with_drm_fd(drm->fd);
 	if (!renderer->wlr_rend) {
 		wlr_log(WLR_ERROR, "Failed to create renderer");
-		goto error_gbm;
+		return false;
 	}
 
 	renderer->allocator = allocator_autocreate_with_drm_fd(&drm->backend,
 		renderer->wlr_rend, drm->fd);
 	if (renderer->allocator == NULL) {
 		wlr_log(WLR_ERROR, "Failed to create allocator");
-		goto error_wlr_rend;
+		wlr_renderer_destroy(renderer->wlr_rend);
+		return false;
 	}
 
 	return true;
-
-error_wlr_rend:
-	wlr_renderer_destroy(renderer->wlr_rend);
-error_gbm:
-	gbm_device_destroy(renderer->gbm);
-	return false;
 }
 
 void finish_drm_renderer(struct wlr_drm_renderer *renderer) {
@@ -58,7 +47,6 @@ void finish_drm_renderer(struct wlr_drm_renderer *renderer) {
 
 	wlr_allocator_destroy(renderer->allocator);
 	wlr_renderer_destroy(renderer->wlr_rend);
-	gbm_device_destroy(renderer->gbm);
 }
 
 bool init_drm_surface(struct wlr_drm_surface *surf,
@@ -287,7 +275,7 @@ static struct wlr_drm_fb *drm_fb_create(struct wlr_drm_backend *drm,
 		}
 	}
 
-	fb->bo = get_bo_for_dmabuf(drm->renderer.gbm, &attribs);
+	fb->bo = get_bo_for_dmabuf(drm->gbm, &attribs);
 	if (!fb->bo) {
 		wlr_log(WLR_DEBUG, "Failed to import DMA-BUF in GBM");
 		goto error_get_dmabuf;

include/backend/drm/drm.h

@@ -62,6 +62,7 @@ struct wlr_drm_backend {
 	int fd;
 	char *name;
 	struct wlr_device *dev;
+	struct gbm_device *gbm;
 
 	size_t num_crtcs;
 	struct wlr_drm_crtc *crtcs;
@@ -79,7 +80,9 @@ struct wlr_drm_backend {
 	struct wl_list fbs; // wlr_drm_fb.link
 	struct wl_list outputs;
 
-	struct wlr_drm_renderer renderer;
+	/* Only initialized on multi-GPU setups */
+	struct wlr_drm_renderer mgpu_renderer;
+
 	struct wlr_session *session;
 
 	uint64_t cursor_width, cursor_height;

include/backend/drm/renderer.h

@@ -13,7 +13,6 @@ struct wlr_buffer;
 
 struct wlr_drm_renderer {
 	struct wlr_drm_backend *backend;
-	struct gbm_device *gbm;
 
 	struct wlr_renderer *wlr_rend;
 	struct wlr_allocator *allocator;