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

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:

quoted

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"

quoted

quoted

quoted

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

quoted

quoted

	compatible = "arm,vexpress-<model>", "arm-vexpress-rs1", "arm-vexpress";

and

quoted

quoted

+	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

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