Re: [PATCH 05/20] bootwrapper: flatdevtree fixes

On Thu, Aug 23, 2007 at 12:48:30PM -0500, Scott Wood wrote:

David Gibson wrote:

quoted

Actually, no - sorry, that's the other problem with this, which I
forgot to mention.  On real OF, the "name" property contains the
node's name *without the unit address*; that is, only the portion
before the '@'.  So your getprop change does not match real OF
behaviour - and real OF behaviour will not do what you want for
dt_get_path().

Ah, OK.

quoted

Actually, in any case, I don't think we want to implement get_path()
this way for real OF.  Better to have get_path() itself as a callback:
on real OF I believe we can directly ask for the full path to a given
phandle, the get name based implementation can then be made specific
to the flat device tree.

Or actually, I think we might be able to come up with a get_path()
implementation for flat tree that's less hideous than repeatedly
calling get_parent() which is an ugly, ugly operation on the flat tree

It's likely to be ugly no matter what, though I'll try to come up with 
something slightly nicer.  If I were doing this code from scratch, I'd 
probably liven the tree first and reflatten it to pass to the kernel.

Eh, probably not worth bothering doing an actual implementation at
this stage - I'll have to redo it for libfdt anyway.

quoted

(and will get worse with libfdt).

Why is that?

flatdevtree uses some of the information it caches in the phandle
context stuff to remember who's the parent of a node.  libfdt uses raw
offsets into the structure, so the *only* way to implement
get_parent() is to rescan the dt from the beginning, keeping track of
parents until reaching the given node.

quoted

quoted

Plus, something might come along that needs to dynamically look for
either name or something else.  It's more flexible this way.

Hrm... "something might come along" just seems contrived to me.

Well, I generally prefer doing things the more flexible way in the 
absence of a good reason not to.  OF returning the bare name is a good 
reason not to.

-- 
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_!
http://www.ozlabs.org/~dgibson