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

[Rob Herring]

On Tue, Jul 16, 2013 at 6:30 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 07/15/2013 05:02 PM, Stephen Warren wrote:
>> On 07/15/2013 01:34 PM, Rob Herring wrote:
>>> On 07/15/2013 01:40 PM, Stephen Warren wrote:
>>>> From: Stephen Warren <swarren at nvidia.com>
>>>>
>>>> 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