backend/drm: add basic support for direct scan-out

backend/drm/drm.c

@@ -820,6 +820,52 @@ static bool drm_connector_schedule_frame(struct wlr_output *output) {
 	return true;
 }
 
+static bool drm_connector_set_dmabuf(struct wlr_output *output,
+		struct wlr_dmabuf_attributes *attribs) {
+	struct wlr_drm_connector *conn = get_drm_connector_from_output(output);
+	struct wlr_drm_backend *drm = get_drm_backend_from_backend(output->backend);
+	if (!drm->session->active) {
+		return false;
+	}
+
+	struct wlr_drm_crtc *crtc = conn->crtc;
+	if (!crtc) {
+		return false;
+	}
+
+	// TODO: check plane input formats
+
+	if (attribs->width != output->width || attribs->height != output->height) {
+		return false;
+	}
+
+	struct gbm_bo *bo = import_gbm_bo(&drm->renderer, attribs);
+	if (bo == NULL) {
+		wlr_log(WLR_ERROR, "import_gbm_bo failed");
+		return NULL;
+	}
+
+	uint32_t fb_id = get_fb_for_bo(bo, gbm_bo_get_format(bo));
+	if (fb_id == 0) {
+		wlr_log(WLR_ERROR, "get_fb_for_bo failed");
+		return false;
+	}
+
+	if (conn->pageflip_pending) {
+		wlr_log(WLR_ERROR, "Skipping pageflip on output '%s'", conn->output.name);
+		return false;
+	}
+
+	if (!drm->iface->crtc_pageflip(drm, conn, crtc, fb_id, NULL)) {
+		wlr_log(WLR_ERROR, "crtc_pageflip failed");
+		return false;
+	}
+
+	conn->pageflip_pending = true;
+	wlr_output_update_enabled(output, true);
+	return true;
+}
+
 static void drm_connector_destroy(struct wlr_output *output) {
 	struct wlr_drm_connector *conn = get_drm_connector_from_output(output);
 	drm_connector_cleanup(conn);
@@ -842,6 +888,7 @@ static const struct wlr_output_impl output_impl = {
 	.get_gamma_size = drm_connector_get_gamma_size,
 	.export_dmabuf = drm_connector_export_dmabuf,
 	.schedule_frame = drm_connector_schedule_frame,
+	.set_dmabuf = drm_connector_set_dmabuf,
 };
 
 bool wlr_output_is_drm(struct wlr_output *output) {

backend/drm/renderer.c

@@ -163,6 +163,30 @@ void post_drm_surface(struct wlr_drm_surface *surf) {
 	}
 }
 
+struct gbm_bo *import_gbm_bo(struct wlr_drm_renderer *renderer,
+		struct wlr_dmabuf_attributes *attribs) {
+	struct gbm_import_fd_modifier_data data = {
+		.width = attribs->width,
+		.height = attribs->height,
+		.format = attribs->format,
+		.num_fds = attribs->n_planes,
+		.modifier = attribs->modifier,
+	};
+
+	if ((size_t)attribs->n_planes > sizeof(data.fds) / sizeof(data.fds[0])) {
+		return NULL;
+	}
+
+	for (size_t i = 0; i < (size_t)attribs->n_planes; ++i) {
+		data.fds[i] = attribs->fd[i];
+		data.strides[i] = attribs->stride[i];
+		data.offsets[i] = attribs->offset[i];
+	}
+
+	return gbm_bo_import(renderer->gbm, GBM_BO_IMPORT_FD_MODIFIER,
+		&data, GBM_BO_USE_SCANOUT);
+}
+
 bool export_drm_bo(struct gbm_bo *bo, struct wlr_dmabuf_attributes *attribs) {
 	memset(attribs, 0, sizeof(struct wlr_dmabuf_attributes));
 

backend/drm/util.c

@@ -184,21 +184,18 @@ uint32_t get_fb_for_bo(struct gbm_bo *bo, uint32_t drm_format) {
 		return id;
 	}
 
-	assert(gbm_bo_get_format(bo) == GBM_FORMAT_ARGB8888);
-	assert(drm_format == DRM_FORMAT_ARGB8888 ||
-		drm_format == DRM_FORMAT_XRGB8888);
-
 	struct gbm_device *gbm = gbm_bo_get_device(bo);
 
 	int fd = gbm_device_get_fd(gbm);
 	uint32_t width = gbm_bo_get_width(bo);
 	uint32_t height = gbm_bo_get_height(bo);
 	uint32_t handles[4] = {gbm_bo_get_handle(bo).u32};
-	uint32_t pitches[4] = {gbm_bo_get_stride(bo)};
+	uint32_t strides[4] = {gbm_bo_get_stride(bo)};
 	uint32_t offsets[4] = {gbm_bo_get_offset(bo, 0)};
+	uint64_t modifiers[4] = {gbm_bo_get_modifier(bo)};
 
-	if (drmModeAddFB2(fd, width, height, drm_format,
+	if (drmModeAddFB2WithModifiers(fd, width, height, drm_format,
-			handles, pitches, offsets, &id, 0)) {
+			handles, strides, offsets, modifiers, &id, DRM_MODE_FB_MODIFIERS)) {
 		wlr_log_errno(WLR_ERROR, "Unable to add DRM framebuffer");
 	}
 

include/backend/drm/renderer.h

@@ -54,6 +54,8 @@ struct gbm_bo *get_drm_surface_front(struct wlr_drm_surface *surf);
 void post_drm_surface(struct wlr_drm_surface *surf);
 struct gbm_bo *copy_drm_surface_mgpu(struct wlr_drm_surface *dest,
 	struct gbm_bo *src);
+struct gbm_bo *import_gbm_bo(struct wlr_drm_renderer *renderer,
+	struct wlr_dmabuf_attributes *attribs);
 bool export_drm_bo(struct gbm_bo *bo, struct wlr_dmabuf_attributes *attribs);
 
 #endif

include/wlr/interfaces/wlr_output.h

@@ -34,6 +34,8 @@ struct wlr_output_impl {
 	bool (*export_dmabuf)(struct wlr_output *output,
 		struct wlr_dmabuf_attributes *attribs);
 	bool (*schedule_frame)(struct wlr_output *output);
+	bool (*set_dmabuf)(struct wlr_output *output,
+		struct wlr_dmabuf_attributes *attribs);
 };
 
 void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,

include/wlr/types/wlr_output.h

@@ -243,6 +243,8 @@ bool wlr_output_preferred_read_format(struct wlr_output *output,
  */
 void wlr_output_set_damage(struct wlr_output *output,
 	pixman_region32_t *damage);
+bool wlr_output_set_dmabuf(struct wlr_output *output,
+	struct wlr_dmabuf_attributes *attribs);
 /**
  * Commit the pending output state. If `wlr_output_attach_render` has been
  * called, the pending frame will be submitted for display.

types/wlr_output.c

@@ -478,6 +478,30 @@ bool wlr_output_commit(struct wlr_output *output) {
 	return true;
 }
 
+bool wlr_output_set_dmabuf(struct wlr_output *output,
+		struct wlr_dmabuf_attributes *attribs) {
+	if (output->frame_pending) {
+		wlr_log(WLR_ERROR, "Tried to swap buffers when a frame is pending");
+		return false;
+	}
+	if (output->idle_frame != NULL) {
+		wl_event_source_remove(output->idle_frame);
+		output->idle_frame = NULL;
+	}
+
+	if (!output->impl->set_dmabuf) {
+		return false;
+	}
+	if (!output->impl->set_dmabuf(output, attribs)) {
+		return false;
+	}
+
+	output->frame_pending = true;
+	output->needs_swap = false;
+	pixman_region32_clear(&output->damage);
+	return true;
+}
+
 void wlr_output_send_frame(struct wlr_output *output) {
 	output->frame_pending = false;
 	wlr_signal_emit_safe(&output->events.frame, output);