[ofw] When one can release CA interface

[Leonid Keller]

fdo_release_resources() in bus_pnp.c releases the last interface with
low-level driver only after IBAL cleanup with the following explanation:

/* AL needs the HCA to stick around until AL cleanup has completed. ...
*/

My question is - why ?
How may/can IBAL proceed to work with HCA after CA has been deregistered
?
What kind of works could be still pending ?