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

On 07/16/2013 07:50 PM, Rob Herring wrote:

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

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

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

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

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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.

quoted

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.

I would strongly hope the BIOS/bootloader/... would have nothing to do
with the DT content. There's a reason that Grant asserted early on that
DTBs shouldn't be part of the BIOS/bootloader, but rather stored
separately, so the DTB could be updated without updating firmware, just
like the kernel. And I see no real problem with a new DTB requiring a
new kernel or even vice-versa to be honest.