Change wlr_session to open every GPU

backend/backend.c

@@ -91,15 +91,9 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		return NULL;
 	}
 
-	int gpu = wlr_session_find_gpu(session);
-	if (gpu == -1) {
-		wlr_log(L_ERROR, "Failed to open DRM device");
-		goto error_session;
-	}
-
 	backend = wlr_multi_backend_create(session);
 	if (!backend) {
-		goto error_gpu;
+		goto error_session;
 	}
 
 	struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
@@ -107,21 +101,36 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		goto error_multi;
 	}
 
-	struct wlr_backend *drm = wlr_drm_backend_create(display, session, gpu);
+	wlr_multi_backend_add(backend, libinput);
+
+	int gpus[8];
+	size_t num_gpus = wlr_session_find_gpus(session, 8, gpus);
+	struct wlr_backend *primary_drm = NULL;
+	wlr_log(L_INFO, "Found %zu GPUs", num_gpus);
+
+	for (size_t i = 0; i < num_gpus; ++i) {
+		struct wlr_backend *drm = wlr_drm_backend_create(display, session, gpus[i]);
 		if (!drm) {
-		goto error_libinput;
+			wlr_log(L_ERROR, "Failed to open DRM device");
+			continue;
+		}
+
+		if (!primary_drm) {
+			primary_drm = drm;
 		}
 
-	wlr_multi_backend_add(backend, libinput);
 		wlr_multi_backend_add(backend, drm);
+	}
+
+	if (!primary_drm) {
+		wlr_log(L_ERROR, "Failed to open any DRM device");
+		goto error_multi;
+	}
+
 	return backend;
 
-error_libinput:
-	wlr_backend_destroy(libinput);
 error_multi:
 	wlr_backend_destroy(backend);
-error_gpu:
-	wlr_session_close_file(session, gpu);
 error_session:
 	wlr_session_destroy(session);
 	return NULL;

backend/drm/backend.c

@@ -42,8 +42,8 @@ static void wlr_drm_backend_destroy(struct wlr_backend *backend) {
 	free(drm);
 }
 
-static struct wlr_egl *wlr_drm_backend_get_egl(struct wlr_backend *_backend) {
-	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)_backend;
+static struct wlr_egl *wlr_drm_backend_get_egl(struct wlr_backend *backend) {
+	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)backend;
 	return &drm->renderer.egl;
 }
 

backend/session/session.c

@@ -191,18 +191,16 @@ bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
 /* Tests if 'path' is KMS compatible by trying to open it.
  * It leaves the open device in *fd_out it it succeeds.
  */
-static bool device_is_kms(struct wlr_session *restrict session,
-	const char *restrict path, int *restrict fd_out) {
-
+static int open_if_kms(struct wlr_session *restrict session, const char *restrict path) {
 	int fd;
 
 	if (!path) {
-		return false;
+		return -1;
 	}
 
 	fd = wlr_session_open_file(session, path);
 	if (fd < 0) {
-		return false;
+		return -1;
 	}
 
 	drmModeRes *res = drmModeGetResources(fd);
@@ -216,26 +214,21 @@ static bool device_is_kms(struct wlr_session *restrict session,
 		goto out_res;
 	}
 
-	if (*fd_out >= 0) {
-		wlr_session_close_file(session, *fd_out);
-	}
-
-	*fd_out = fd;
-
 	drmModeFreeResources(res);
-	return true;
+	return fd;
 
 out_res:
 	drmModeFreeResources(res);
 out_fd:
 	wlr_session_close_file(session, fd);
-	return false;
+	return -1;
 }
 
 /* Tries to find the primary GPU by checking for the "boot_vga" attribute.
  * If it's not found, it returns the first valid GPU it finds.
  */
-int wlr_session_find_gpu(struct wlr_session *session) {
+size_t wlr_session_find_gpus(struct wlr_session *session,
+		size_t ret_len, int ret[static ret_len]) {
 	struct udev_enumerate *en = udev_enumerate_new(session->udev);
 	if (!en) {
 		wlr_log(L_ERROR, "Failed to create udev enumeration");
@@ -247,9 +240,13 @@ int wlr_session_find_gpu(struct wlr_session *session) {
 	udev_enumerate_scan_devices(en);
 
 	struct udev_list_entry *entry;
-	int fd = -1;
+	size_t i = 0;
 
 	udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(en)) {
+		if (i == ret_len) {
+			break;
+		}
+
 		bool is_boot_vga = false;
 
 		const char *path = udev_list_entry_get_name(entry);
@@ -258,15 +255,13 @@ int wlr_session_find_gpu(struct wlr_session *session) {
 			continue;
 		}
 
-		/*
 		const char *seat = udev_device_get_property_value(dev, "ID_SEAT");
 		if (!seat)
 			seat = "seat0";
-		if (strcmp(session->seat, seat) != 0) {
+		if (session->seat[0] && strcmp(session->seat, seat) != 0) {
 			udev_device_unref(dev);
 			continue;
 		}
-		*/
 
 		// This is owned by 'dev', so we don't need to free it
 		struct udev_device *pci =
@@ -279,27 +274,25 @@ int wlr_session_find_gpu(struct wlr_session *session) {
 			}
 		}
 
-		// We already have a valid GPU
-		if (!is_boot_vga && fd >= 0) {
-			udev_device_unref(dev);
-			continue;
-		}
-
-		path = udev_device_get_devnode(dev);
-		if (!device_is_kms(session, path, &fd)) {
+		int fd = open_if_kms(session, udev_device_get_devnode(dev));
+		if (fd < 0) {
 			udev_device_unref(dev);
 			continue;
 		}
 
 		udev_device_unref(dev);
 
-		// We've found the primary GPU
+		ret[i] = fd;
 		if (is_boot_vga) {
-			break;
+			int tmp = ret[0];
+			ret[0] = ret[i];
+			ret[i] = tmp;
 		}
+
+		++i;
 	}
 
 	udev_enumerate_unref(en);
 
-	return fd;
+	return i;
 }

include/wlr/backend/session.h

@@ -78,6 +78,7 @@ void wlr_session_signal_add(struct wlr_session *session, int fd,
  */
 bool wlr_session_change_vt(struct wlr_session *session, unsigned vt);
 
-int wlr_session_find_gpu(struct wlr_session *session);
+size_t wlr_session_find_gpus(struct wlr_session *session,
+	size_t ret_len, int ret[static ret_len]);
 
 #endif