Mis?use of aliases

[David Gibson]

On Fri, Jul 13, 2012 at 07:30:42PM -1000, Mitch Bradley wrote:
> > I'm not sure this is really a good use of aliases. UARTs use aliases
> > because it is important that the UART number to tty number is known and
> > fixed.
> 
> This brings up an issue that I've been meaning to comment on.
> 
> The use of phandle-valued properties in the aliases node causes real OFW
> implementations some amount of heartburn.  The Open Firmware standard
> says that the properties in /aliases are string-valued.  That's
> important, because aliases are shorthand for fragments of full device
> specifiers (pathnames that can include arguments to nodes).  Phandles
> can point to nodes, but can't be relative, and can't encode
> per-node-component arguments.

Um, so, properties in /aliases should not have phandle values, flat
tree or otherwise.  Has this been seen in the wild, or are you being
misled by the fact that dtc's reference-to-phandle and
reference-to-path syntax is very similar:

	prop = <&fred>;
Will generate a phandle valued property, but
	prop = &fred;
Will generate a string (path) valued property.

> For binding a Linux unit number to a device node, I would prefer to
> decorate the node with a property like "linux,unit#", instead of
> breaking the standard semantics of /aliases.

I don't see how using aliases for unit numbering (inherently) breaks
the semantics of /aliases.  If phandle valued properties are being
used that is wrong, but it's not necessary for the unit numbering
anyway.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
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