Re: [RFC][PATCH 6/8] Walnut DTS

On Mon, 2007-07-16 at 16:55 -0500, Scott Wood wrote:

Benjamin Herrenschmidt wrote:

quoted

I would personally be inclined to define that whatever spec we come up
with always require #address-cells/#size-cells for any node that can
have either device children or interrupt children, and ban default
values alltogether.

When is #size-cells used in the interrupt tree at all?

It's not, sorry, my fingers typed a bit too fast :-)

And given the odd behavior of using an interrupt map in an interrupt 
parent that is not the device parent (you're potentially using keys from 
different domains that could clash, be a different sizes, etc), if we 
make any changes in that regard, I'd forbid interrupt maps in interrupt 
controllers with no device children, and thus #address-cells has no 
meaning there.

No, interrupt maps are useful in devices with no children in some corner
cases. Remember that a map doesnt need to use the address part of the
source specifier, thus it can be used to do a pure domain->domain
conversion of the irq numbers, what sort of thing. The map has the added
advantage that today, it's the only mechanism that allows you to specify
different interrupt-parents through the same nexus, which is useful for
4xx.

Ben.