drm/dp/mst: split connector registration into two parts (v2)

In order to cache the EDID properly for tiled displays, we
need to retrieve it before we register the connector with
userspace, otherwise userspace can call get resources
and try and get the edid before we've even cached it.

This fixes some problems when hotplugging mst monitors,
with X/mutter running. As mutter seems to get 0 modes
for one of the monitors in the tile.

v2: fix warning in radeon
handle tile setting in cached path rather than
get edid path.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c b/drivers/gpu/drm/radeon/radeon_dp_mst.c
index 5e09c06..6cddae4 100644
--- a/drivers/gpu/drm/radeon/radeon_dp_mst.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c
@@ -265,7 +265,6 @@
 {
 	struct radeon_connector *master = container_of(mgr, struct radeon_connector, mst_mgr);
 	struct drm_device *dev = master->base.dev;
-	struct radeon_device *rdev = dev->dev_private;
 	struct radeon_connector *radeon_connector;
 	struct drm_connector *connector;
 
@@ -286,12 +285,19 @@
 	drm_object_attach_property(&connector->base, dev->mode_config.path_property, 0);
 	drm_mode_connector_set_path_property(connector, pathprop);
 
+	return connector;
+}
+
+static void radeon_dp_register_mst_connector(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct radeon_device *rdev = dev->dev_private;
+
 	drm_modeset_lock_all(dev);
 	radeon_fb_add_connector(rdev, connector);
 	drm_modeset_unlock_all(dev);
 
 	drm_connector_register(connector);
-	return connector;
 }
 
 static void radeon_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr,
@@ -324,6 +330,7 @@
 
 struct drm_dp_mst_topology_cbs mst_cbs = {
 	.add_connector = radeon_dp_add_mst_connector,
+	.register_connector = radeon_dp_register_mst_connector,
 	.destroy_connector = radeon_dp_destroy_mst_connector,
 	.hotplug = radeon_dp_mst_hotplug,
 };