[This followup was posted to gmane.os.netbsd.devel.kernel and a copy was 
sent to the cited author.]

In article <20060316065952.GW3735@che.ojctech.com>, dyoung@pobox.com 
says...

> 
> I figure they do it either because of a defect in the Cardbus API, or
> because the Cardbus front-ends are "cut & paste" copies of each other.
> We badly need to extract a subroutine or three from the sources in
> dev/cardbus/.

It does look that way, If I actually understood why the value is written 
back, I could do the required changes. Looks like I'm going to have to 
start emailing the Authors of those drivers and find out which one wrote 
the first one ;)

Thanks. Phil.