Re: [PATCH 1/3 v3] Add StorCenter DTS first draft.

[Josh Boyer <jwboyer@linux.vnet.ibm.com>]

On Wed, 23 Jan 2008 11:33:16 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> 
> > > +
> > > +               mpic: interrupt-controller@40000 {
> > > +                       #interrupt-cells = <2>;
> > > +                       #address-cells = <0>;
> > 
> > Is #address-cells needed?  There are no child nodes.
> 
> It's preferrable for interrupt controllers as #address-cells of the
> parent interrupt controller defines the size of the interrupt unit
> specifier in the child in the interrupt tree.
> 
> I think there's an ongoing argument as to whether the absence of
> #address-cells should be the same as #address-cells = 0 in that specific
> case but I'm not sure the code does the right thing so let's have it
> explicit.

The code doesn't handle the lack of #address-cells in nodes where
there is an interrupt-map. It pukes if there is no reg property and
addrsize != 0. In the absence of the #address-cells property, it will
try to look at the parent's #address-cells, and if that lacks it, it
will assign 2 which it then merrily decides is incorrect.

josh