newbus' ivar's limitation..

[Arnaud Lacombe]

Hi folks,

Ok, yet another Newbus' limitation. Assuming a device exports more
than one interface, and one of its child has need to use more than one
interface, each interfaces cannot register, concurrently, its own
ivar. While I try to always have a single child per
interface/resource, I need to keep some compatibility with the old way
of doing thing (POLA wrt. drivers I cannot/will not convert and
userland). So, it would have been nice if ivar had been per-interface,
not global and unique to one device.

Unless I am mistaken, ivar are the only way for a parent can transmit
information to a child. I can not simply implement a new METHOD to get
that ivar as the device implements multiple time the same function
(actually, up to 4 time for one, 3 for the other, with possible
crossovers...), each one physically distinct. Each child is being tied
to a pair. Thus, I need to pass each child discriminator(s) for each
interfaces right after having been *created*, which cannot be done
later on. Of course, it is out-of-question to have crossover in the
interfaces definitions.

The best way I could achieve this currently is to pass the child's
device to its parent, and do a lookup based on that pointer to get
information I need, but erk....

my 1c,
 - Arnaud