Re: [PATCH V2 5/5] ARM: remove #gpio-ranges-cells property

On Tue, Jul 16, 2013 at 6:30 PM, Stephen Warren [off-list ref] wrote:

On 07/15/2013 05:02 PM, Stephen Warren wrote:

quoted

On 07/15/2013 01:34 PM, Rob Herring wrote:

quoted

On 07/15/2013 01:40 PM, Stephen Warren wrote:

quoted

From: Stephen Warren <redacted>

This property is no longer required by the GPIO binding. Remove it.

Won't this break compatibility with older kernel? It is one thing to
deprecate, but removal is another. If the relevant maintainers don't
care, then I guess it is fine.

Yes.

I had originally hoped this could sneak in late for 3.11, but I suppose
it's too late now. vf610.dtsi is a new file in 3.11 so has no legacy to
protect.

Admittedly, the #gpio-cells property was added into the SPEAr files in 3.10.

One more thought here:

I know DT bindings are supposed to evolve so that a new kernel will
support arbitrary old DTs. I'll call that backwards-compatibility for
the DT parsing code.

That is the more common case.

However, this situation is the reverse; this patch would prevent a new
DT running on an older kernel. I'll call that forwards-compatibility.
I'm not sure if the intent is to support this or not? It's certainly the
first I explicitly thought about compatibility in this direction...

So you would be okay if your computer stopped booting a kernel after a
BIOS update? It's the same deal. It's both forwards and backwards
compatibility that is needed.

Rob