dtc: Empty ranges property: #cells-size warning

[David Gibson]

On Wed, Oct 21, 2009 at 06:41:22PM +0200, Segher Boessenkool wrote:
> > when changing #cells-size from 1 to 2 in the root node (to support >= 4GB
> > of
> 
> You mean "#size-cells".
> 
> > RAM in katmai.dts) I get the following warning:
> >
> > Warning (ranges_format): /plb has empty "ranges" property but its
> > #size-cells
> > (1) differs from / (2)
> >
> > I could change #cells-size to 2 in the plb node as well. But this not
> > really
> > what I want, because of it's child nodes.
> >
> > So my questions is: How can I solve this problem? Perhaps this warning
> > should
> > be removed from dtc?
> 
> No, the warning is correct, and your device tree is in error.
> 
> An empty "ranges" property means that the child address space is
> identical to the parent address space, which isn't the case here.
> 
> You should resolve this by using a non-empty "ranges" property,
> instead.  If e.g. the address space is 1GB, and located at 0, you
> would do
> 
>    < 0    0 0    0x40000000 >
> (child) (parent)    (size)

Exactly.  An empty ranges property makes no sense if the parent and
child address spaces aren't identical.  You need an explicit ranges
property to show how the child address space is embedded in the
parent's.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
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