[PATCH 3/5] ARM: vexpress: Add DT support in v2m

[Dave Martin]

On Wed, Nov 16, 2011 at 05:07:51PM +0000, Pawel Moll wrote:
> On Wed, 2011-11-16 at 16:59 +0000, Rob Herring wrote:
> > It has nothing to do with taste and obviously documentation changes over
> > time. I'm going to start naming everything with legacy because someday
> > it all will be...
> > 
> > It's about how you create compatible strings. They should not be
> > generic, but specific to particular hardware version. If you happen to
> > be compatible with older h/w then you can claim compatibility with that
> > older h/w.
> 
> Notice that it's not:
> 
> 	compatible=legacy
> 
> not even:
> 
> 	compatible=arm,legacy
> 
> It's:
> 	
> 	compatible=arm,vexpress-legacy
> 
> A specific variant of Versatile Express hardware. It's just that the
> "legacy" word carries some meaning. Would it looked better if it was
> called:
> 
> 	compatible=arm,vexpress-nalatenskap
> 
> ? (thanks, google translate ;-)

Come to think of it, is the problem here that we're trying to describe
the _motherboard_ using the compatible property on the root node.
This is why I talked about universal/generic features -- the set of
features common to all platforms sharing a single motherboard
configuration.

Arguably that's wrong, and that compatible property belongs on the
motherboard node itself, so:

/ {
	compatible = "arm,vexpress-ca9x4"


> 
> > >> If you defined the property when the
> > >> original vexpress was designed, it never would have had legacy in the
> > >> name. Generally speaking you never change bindings on old platforms.
> > >>
> > >> So I would have "arm,vexpress" mean legacy and "arm,vexpress-rs1" be the
> > >> new memory map.
> > > 
> > > I'd rather second Dave's idea of having
> > > 
> > >>> 	compatible = "arm,vexpress-<model>", "arm-vexpress-rs1", "arm-vexpress";
> > > 
> > > and
> > > 
> > >>> +	compatible = "arm,vexpress-<model>", "arm,vexpress-legacy", "arm-vexpress";
> > 
> > If arm,vexpress-ca9 is the only legacy platform, then just drop
> > arm,vexpress-legacy altogether.
> 
> It's not. There is additional one, which is not publicly available, but
> is using the motherboard in legacy mode.
> 
> Cheers!
> 
> Paweł
> 
>