On Tue, Dec 06, 2022 at 09:31:49AM -0600, Rob Herring wrote: > On Mon, Nov 21, 2022 at 9:31 AM Andy Shevchenko > <andriy.shevchenko@xxxxxxxxx> wrote: > > > > On Mon, Nov 21, 2022 at 03:23:53PM +0100, Krzysztof Kozlowski wrote: > > > On 21/11/2022 15:11, Andy Shevchenko wrote: > > > > On Mon, Nov 21, 2022 at 02:52:37PM +0100, Krzysztof Kozlowski wrote: > > > >> On 21/11/2022 13:59, Andy Shevchenko wrote: > > > >>> > > > >>> Hi, Rob and Krzysztof! > > > >>> > > > >>> Today on SO one question [1] was popped up, and I, remembering a bit of > > > >>> the code of device properties in the Linux kernel, was a bit surprised of it > > > >>> in a way that reading DT specification (0.4-rc1 as of today) doesn't clarify > > > >>> that either. > > > >>> > > > >>> Can the specification be a bit more clear about that? Or is it me and the OP of > > > >>> that question who missed something in the DT spec? > > Please use devicetree-spec list for questions like this because it's a > spec question and I only see these on my periodic search for non-patch > emails. Sure. I will try to not forget this next time I will have a question against DT spec (I don't expect this will be anytime soon, though). > > > >>> [1]: https://stackoverflow.com/questions/74517569/reading-tuples-in-a-devicetree > > > >> > > > >> I saw question on Stackoverflow and I saw there answers, but what is the > > > >> question to us? > > > > > > > > Does the specification allows mixed types of the values in the same property? > > > > Because reading it doesn't give a hint. > > > > > > I think DT spec allows it ("Format is specific to the property. See the > > > property definition.") > > > > And the quoted sentence confuses me. Is it related to _defined_ only properties > > (that are in the same document) or is it to any property, then what does the > > second part actually mean in the latter case: "see the property definition". > > Where? > > Any property in the schemas. (I would say if not in the spec, but > everything in the spec should have a schema.) Maybe we should add these words explicitly there? > > It might be though it's lack of my understanding the English language > > (not a native speaker). > > > > > but DT schema mostly not (finite list of property > > > types). To some level DT schema accepts mixes, e.g. phandle-array > > > containing phandle and offsets, but that's because phandle is actually > > > also a number (dtschema/schemas/types.yaml). > > At the spec level, properties are just byte strings. They can be > anything including a file (i.e. FIT images). In theory, you could make > properties C structs if you wanted. > > However, since there is 0 type or field size information in the DT > itself, we don't mix data types or sizes. That's enforced at the > schema level and by what APIs we have to read properties. Thanks for clarification! -- With Best Regards, Andy Shevchenko
