Subject: Re: [PATCH 15/16] Add device tree for Ebony

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 14 Feb 2007 12:51:06 +1100

> > > +	UIC0: interrupt-controller { /* UIC0 */
> > 
> > > +		#address-cells = <0>;
> > > +		#size-cells = <0>;
> > 
> > #address-cells = 0 never makes sense.
> 
> Why not?  Children of this node have and need no reg property, and no
> meaningful address.  Sounds like #address-cells = 0 to me.

In fact, not only it does make perfect sense but it's also routinely
used for ... interrupt controllers :-) That's among others why the
interrupt map entries "second" part usually doesn't contain the address
cells.

> > > +	plb {
> > > +		device_type = "soc";
> > > +		compatible = "ibm,plb-440gp", "ibm,plb4";
> > > +		ranges;
> > 
> > You need a #address-cells, #size-cells here.
> 
> Why?  The values inherited from the root node are perfectly ok here.

Inheriting values is out of spec. The kernel somewhat does it but that's
a bad habit, we should always have them explicit.

Ben.