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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [RFC][PATCH 6/8] Walnut DTS
Date: Wed, 18 Jul 2007 15:53:54 +0200
To: Scott Wood <scottwood@freescale.com>
Cc: Yoder Stuart-B08248 <stuart.yoder@freescale.com>, linuxppc-dev@ozlabs.org
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>> See above. Besides, as I said, default values are crap. And no,  
>> it's not
>> obvious which nodes define a physical address space or not, at  
>> least not
>> for a generic parser.
>
> The obvious way (which indeed isn't what the suggested algorithm  
> does --
> but the suggested algorithm doesn't do anything sensible) is that  
> if you
> got to the node via an interrupt-parent or interrupt-map, it  
> doesn't use
> #address-cells, and if you got to it by going to the regular device  
> tree
> parent, it does.
>
> Pretty much any time you use the unit address in a context other  
> than the
> bus parent, things cease making sense.

Yes indeed.  The problem with your suggested "obvious way"
is that you wouldn't get a unit address included if your
interrupt-map points (for some entry) at your device tree
parent, either.  Not all that hypothetical.


Segher