> 
> So, I'm still waiting for an explanation of the tangible benefit
> of forcing all ports using the driver to call a function on each
> access to a device register...

The only one I can think of is the case where you have two different
types of busses in the same computer. By using a function pointer, you
test once, when you set the pointer's value. With a header-included
solution, you have to test each time.

On the flip side, there could well be times (when you have only one
bus type) where the header solution would be better, as you do all
the resolution at compile time. You don't need to use a pointer to
tell you what to do as you already know. (so actually this is a vote
against function pointers :-)

I'm interested to hear other reasons.

Take care,

Bill