The connectors enumerated by the GETRESOURCES ioctl may not be fully
initialized yet wrt. to the state set up during connector registration
(for instance the connector's debugfs/sysfs interfaces may not exist
yet). This can happen in two ways:
1. Connectors initialized and added to the
drm_mode_config::connector_list during driver loading will be visible
to the GETRESOURCES ioctl caller once the driver is registered via
drm_dev_register()->drm_minor_register(DRM_MINOR_PRIMARY) and before
the connectors are registered via drm_dev_register()->
drm_modeset_register_all().
2. Dynamic connectors (MST) - after being initialized - may be added to
the connector_list after the driver is loaded and registered and before
the connector's userspace interfaces (debugfs, sysfs etc.) are added
in drm_connector_dynamic_register().
A solution for 1. would be to register the driver only after the
connectors are registered, for 2. to add the connector to connector_list
only after the userspace interfaces are registered.
The fix would require a bigger change, not the topic of this patchset,
so adding only a FIXME comment here.
Suggested-by: Simona Vetter <simona.vetter@xxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/drm_mode_config.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 37d2e0a4ef4be..8642a2fb25a90 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -150,6 +150,15 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
drm_connector_list_iter_begin(dev, &conn_iter);
count = 0;
connector_id = u64_to_user_ptr(card_res->connector_id_ptr);
+ /*
+ * FIXME: the connectors on the list may not be fully initialized yet,
+ * if the ioctl is called before the connectors are registered. (See
+ * drm_dev_register()->drm_modeset_register_all() for static and
+ * drm_connector_dynamic_register() for dynamic connectors.)
+ * The driver should only get registered after static connectors are
+ * fully initialized and dynamic connectors should be added to the
+ * connector list only after fully initializing them.
+ */
drm_for_each_connector_iter(connector, &conn_iter) {
/* only expose writeback connectors if userspace understands them */
if (!file_priv->writeback_connectors &&
--
2.44.2
