[Ksummit-2013-discuss] DT bindings as ABI [was: Do we have people interested in device tree janitoring / cleanup?]

[Grant Likely]

On Fri, Jul 26, 2013 at 8:21 AM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Fri, Jul 26, 2013 at 10:14:32AM -0400, jonsmirl at gmail.com wrote:
>> Yes, yes - that's why the schema should be written down and used as a
>> validation input to dtc. Then dtc can spit out errors for non-standard
>> items. There would be two versions - the standard one and a legacy one
>> that includes the standard one plus the hacks that can't be undone.
>>
>> But more importantly it provides a framework for people creating new
>> node definitions. Now they can't work in a vacuum and come up with
>> random names and structure for everything.
>>
>> Most of the problems express in the thread would go away if the schema
>> was written down and discussed. The rule going forward would be no new
>> nodes that aren't part of the standard schema.
>
> So this is why I'm seeing patches just a short time ago removing existing
> compatible strings from the DT descriptions and associated driver, and
> replacing them with new ones... meaning that the old DT files won't work
> with newer kernels.
>
> What that means is using the descriptions as the schema won't catch that
> because they're changing those as well to match.
>
> There's a solution to that: dtc becomes a separate project external to
> the kernel which also contains the schemas that it verifies against.
> That way, if you want to make changes such as that above, you need to
> get it past not only kernel people but also past dtc maintainers -
> which increases the chances of such stuff being caught.

+1

dtc has always been a separate project that happens to be mirrored in
the kernel tree, but the bindings need to come out be turned into
schema that can be validated.

g.