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

Benjamin Herrenschmidt wrote:

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.

OK...  but if you're doing a pure IRQ number conversion, the only useful 
#address-cells would be zero, which makes it a reasonable default IMHO 
(unlike the arbitrary 2 for regular traversal).

-Scott