-Fix potential race condition when initializing the layers
with multiple drivers by verifying the usable drivers and layers
before init of the final ddi tables.
-Document the reasons for requiring ddi table init before driver init
checks can be done.
-Fix potential race condition when initializing the layers with multiple drivers by verifying the usable drivers and layers before init of the final ddi tables.
-Document the reasons for requiring ddi table init before driver init checks can be done.