Re: Mis?use of aliases

On Fri, Jul 13, 2012 at 07:30:42PM -1000, Mitch Bradley wrote:

quoted

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
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				| _way_ _around_!
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