backend/drm: implement drm lease function

backend/drm/drm.c

@@ -1262,6 +1262,15 @@ void scan_drm_connectors(struct wlr_drm_backend *drm) {
 
 			get_drm_connector_props(drm->fd, wlr_conn->id, &wlr_conn->props);
 
+			uint64_t non_desktop;
+			if (get_drm_prop(drm->fd, wlr_conn->id,
+						wlr_conn->props.non_desktop, &non_desktop)) {
+				if (non_desktop == 1) {
+					wlr_log(WLR_INFO, "Non-desktop connector");
+				}
+				wlr_conn->output.non_desktop = non_desktop;
+			}
+
 			size_t edid_len = 0;
 			uint8_t *edid = get_drm_prop_blob(drm->fd,
 				wlr_conn->id, wlr_conn->props.edid, &edid_len);
@@ -1469,3 +1478,101 @@ void destroy_drm_connector(struct wlr_drm_connector *conn) {
 	wl_list_remove(&conn->link);
 	free(conn);
 }
+
+/* TODO: make the function return a `wlr_drm_lease` to provide a destroy event
+ * that can be fired when the kernel notifies us through uevent that the lease
+ * has been destroyed
+ */
+int wlr_drm_create_lease(struct wlr_output **outputs, size_t n_outputs,
+		uint32_t *lessee_id) {
+	assert(outputs);
+
+	if (n_outputs == 0) {
+		wlr_log(WLR_ERROR, "Can't lease 0 outputs");
+		return -1;
+	}
+
+	struct wlr_drm_backend *drm =
+			get_drm_backend_from_backend(outputs[0]->backend);
+
+	int n_objects = 0;
+	uint32_t objects[4 * n_outputs + 1];
+	for (size_t i = 0; i < n_outputs; ++i) {
+		struct wlr_drm_connector *conn =
+				get_drm_connector_from_output(outputs[i]);
+		assert(conn->lessee_id == 0);
+
+		if (conn->backend != drm) {
+			wlr_log(WLR_ERROR, "Can't lease output from different backends");
+			return -1;
+		}
+
+		objects[n_objects++] = conn->id;
+		wlr_log(WLR_DEBUG, "Connector %d", conn->id);
+
+		if (!conn->crtc) {
+			wlr_log(WLR_ERROR, "Connector has no CRTC");
+			return -1;
+		}
+
+		objects[n_objects++] = conn->crtc->id;
+		wlr_log(WLR_DEBUG, "CRTC %d", conn->crtc->id);
+
+		objects[n_objects++] = conn->crtc->primary->id;
+		wlr_log(WLR_DEBUG, "Primary plane %d", conn->crtc->primary->id);
+
+		if (conn->crtc->cursor) {
+			wlr_log(WLR_DEBUG, "Cursor plane %d", conn->crtc->cursor->id);
+			objects[n_objects++] = conn->crtc->cursor->id;
+		}
+	}
+
+	assert(n_objects != 0);
+
+	wlr_log(WLR_DEBUG, "Issuing DRM lease with the %d objects", n_objects);
+	int lease_fd = drmModeCreateLease(drm->fd, objects, n_objects, 0,
+			lessee_id);
+	if (lease_fd < 0) {
+		return lease_fd;
+	}
+
+	wlr_log(WLR_DEBUG, "Issued DRM lease %"PRIu32, *lessee_id);
+	for (size_t i = 0; i < n_outputs; ++i) {
+		struct wlr_drm_connector *conn =
+				get_drm_connector_from_output(outputs[i]);
+		conn->lessee_id = *lessee_id;
+		conn->crtc->lessee_id = *lessee_id;
+	}
+
+	return lease_fd;
+}
+
+bool wlr_drm_backend_terminate_lease(struct wlr_backend *backend,
+		uint32_t lessee_id) {
+	wlr_log(WLR_DEBUG, "Terminating DRM lease %d", lessee_id);
+
+	assert(backend);
+	struct wlr_drm_backend *drm = get_drm_backend_from_backend(backend);
+
+	int r = drmModeRevokeLease(drm->fd, lessee_id);
+	if (r < 0) {
+		wlr_log_errno(WLR_DEBUG, "Failed to terminate lease");
+	}
+
+	struct wlr_drm_connector *conn;
+	wl_list_for_each(conn, &drm->outputs, link) {
+		if (conn->lessee_id == lessee_id) {
+			conn->lessee_id = 0;
+			/* Will be re-initialized in scan_drm_connectors */
+		}
+	}
+
+	for (size_t i = 0; i < drm->num_crtcs; ++i) {
+		if (drm->crtcs[i].lessee_id == lessee_id) {
+			drm->crtcs[i].lessee_id = 0;
+		}
+	}
+
+	return r >= 0;
+}
+

backend/drm/properties.c

@@ -25,6 +25,7 @@ static const struct prop_info connector_info[] = {
 	{ "EDID", INDEX(edid) },
 	{ "PATH", INDEX(path) },
 	{ "link-status", INDEX(link_status) },
+	{ "non-desktop", INDEX(non_desktop) },
 	{ "subconnector", INDEX(subconnector) },
 	{ "vrr_capable", INDEX(vrr_capable) },
 #undef INDEX

include/backend/drm/drm.h

@@ -37,6 +37,7 @@ struct wlr_drm_plane {
 
 struct wlr_drm_crtc {
 	uint32_t id;
+	uint32_t lessee_id;
 
 	// Atomic modesetting only
 	uint32_t mode_id;
@@ -119,6 +120,7 @@ struct wlr_drm_connector {
 	enum wlr_drm_connector_status status;
 	bool desired_enabled;
 	uint32_t id;
+	uint32_t lessee_id;
 
 	struct wlr_drm_crtc *crtc;
 	uint32_t possible_crtcs;

include/backend/drm/properties.h

@@ -18,6 +18,7 @@ union wlr_drm_connector_props {
 		uint32_t path;
 		uint32_t vrr_capable; // not guaranteed to exist
 		uint32_t subconnector; // not guaranteed to exist
+		uint32_t non_desktop;
 
 		// atomic-modesetting only
 

include/wlr/backend/drm.h

@@ -33,6 +33,20 @@ bool wlr_output_is_drm(struct wlr_output *output);
  */
 uint32_t wlr_drm_connector_get_id(struct wlr_output *output);
 
+/**
+ * Leases a given output to the caller. The output must be from the associated
+ * DRM backend.
+ * Returns a valid opened DRM FD or -1 on error.
+ */
+int wlr_drm_create_lease(struct wlr_output **outputs, size_t n_outputs,
+		uint32_t *lessee_id);
+
+/**
+ * Terminates a given lease. The output will be owned again by the backend
+ */
+bool wlr_drm_backend_terminate_lease(struct wlr_backend *backend,
+	uint32_t lessee_id);
+
 /**
  * Add mode to the list of available modes
  */

include/wlr/types/wlr_output.h

@@ -141,6 +141,9 @@ struct wlr_output {
 	bool frame_pending;
 	float transform_matrix[9];
 
+	// true for example with VR headsets
+	bool non_desktop;
+
 	struct wlr_output_state pending;
 
 	// Commit sequence number. Incremented on each commit, may overflow.