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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [PATCH 15/16] Add device tree for Ebony
Date: Thu, 15 Feb 2007 02:00:52 +0100
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org, David Gibson <david@gibson.dropbear.id.au>
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>>> Note that the "open-pic" node does not have a "#address-cells"
>>> property, so that  the number of cells for the parent unit interrupt
>>> specifiers is 2 (which is the value of its "#interrupt-cells"
>>> property).

> Yes, "missing" is equivalent to 0,

...and the reason for that is that nodes without physical
children should not _have_ a "#address-cells" property.

> but the common practice has always
> been to specify it explicitely. Check existing Apple and IBM
> device-trees for example.

You do realise how many other borderline (or outright
wrong) things are done in those trees, right?

It doesn't really hurt to have a "#a = 0" prop, but it's
better to just not have a #a prop if you shouldn't have one.


Segher