leftovers from older (never merged into upstream) KMS designs where modes
where set using their ID, including support to add/remove modes.
+- Make ->funcs and ->helper_private vtables optional. There's a bunch of empty
+ function tables in drivers, but before we can remove them we need to make sure
+ that all the users in helpers and drivers do correctly check for a NULL
+ vtable.
+
+- Cleanup up the various ->destroy callbacks. A lot of them just wrapt the
+ drm_*_cleanup implementations and can be removed. Some tack a kfree() at the
+ end, for which we could add drm_*_cleanup_kfree(). And then there's the (for
+ historical reasons) misnamed drm_primary_helper_destroy() function.
+
Better Testing
==============