On 05/19/2010 04:47 PM, Grant Likely wrote:
On Wed, May 19, 2010 at 3:37 PM, Scott Wood<scottw...@freescale.com> wrote:
I believe the only part of this that is new with ePAPR is that it asks that
the interrupt controller address cells be explicitly specified, as it's a
bit icky for it to default to 2 in some contexts and 0 in others.
Hmmm. I've not seen that before. On the 5200 the value of
#address-cells for interrupt controllers has apparently defaulted to
<0> so I've never encountered or thought about it. I'm not even sure
what #address-cells != 0 would mean in the context of interrupt
mapping, or where it would be relevant.
The address component is mainly used in PCI interrupt mapping, where
each slot has a distinct wiring.
It would be weird to see it on a normal interrupt controller, but
explicitly setting it to zero helps avoid someone deciding that an
interrupt controller ought to have a child node for whatever reason
(this was an issue with MPIC), setting address cells to something
non-zero, and messing up interrupt maps.
-Scott
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