On Fri, Nov 04, 2022 at 10:52:22AM -0400, Krzysztof Kozlowski wrote: > On 01/11/2022 09:07, Rob Herring wrote: > > On Fri, Oct 28, 2022 at 07:37:01PM -0400, Krzysztof Kozlowski wrote: > >> It is useful to start from existing bindings when writing new ones, > >> especially when one does not know that much DT schema. However we have > >> several bindings which are not the best examples, so people tend to copy > >> their issues into new bindings. > >> > >> Beginners also might not know how to achieve some more complex solutions > >> in DT schema, e.g. how one of two properties should be required by the > >> bindings. Some of such solutions are already in example-schema.yaml, > >> but several other are missing. Add reference with such re-usable > >> design-patterns. > > > > My main concern here is what's a good example today is not tomorrow... > > Yes, I agree. The problem I want to solve is some folks copy-paste some > existing schema as starting point and then are surprised when receive > basic style feedback. > > Of course the optimal solution would be to make all schemas in same > (proper) style, but this is going take some time... > > How to solve this problem other way? I don't know. shrug > >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> > >> --- > >> .../devicetree/bindings/examples.rst | 63 +++++++++++++++++++ > >> Documentation/devicetree/bindings/index.rst | 1 + > >> 2 files changed, 64 insertions(+) > >> create mode 100644 Documentation/devicetree/bindings/examples.rst > >> > >> diff --git a/Documentation/devicetree/bindings/examples.rst b/Documentation/devicetree/bindings/examples.rst > >> new file mode 100644 > >> index 000000000000..710eea81d8b7 > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/examples.rst > >> @@ -0,0 +1,63 @@ > >> +.. SPDX-License-Identifier: GPL-2.0 > >> + > >> +Examples of Devicetree Bindings to use a base > >> +============================================= > >> + > >> +Following Devicetree Bindings in DT Schema are a known good starting point when > >> +writing new bindings: > >> + > >> +1. Simple SPI device: > >> + Documentation/devicetree/bindings/iio/adc/maxim,max11205.yaml > >> + > >> +2. PMIC (MFD) with several sub-devices: > >> + Documentation/devicetree/bindings/mfd/mediatek,mt6370.yaml > >> + > >> +3. Battery charger (power supply): > >> + Documentation/devicetree/bindings/power/supply/bq256xx.yaml > >> + (but use vendor prefix in filename) > >> + > >> +4. Clock controller for several devices with different clock inputs: > >> + Documentation/devicetree/bindings/clock/qcom,mmcc.yaml > >> + > >> +5. GPIO controller: > >> + Documentation/devicetree/bindings/gpio/qcom,wcd934x-gpio.yaml > >> + > >> + > >> +Re-usable design patterns when writing your own bindings > >> +======================================================== > >> + > >> +Following bindings show how to use common pattern of writing bindings: > >> + > >> +1. Property required and present only for one variant. Property cannot appear > >> + on other variants: > >> + Documentation/devicetree/bindings/example-schema.yaml > >> + Line: 212 > >> + > >> +2. Excluding properties, but none are required: > >> + Documentation/devicetree/bindings/mfd/samsung,s5m8767.yaml > >> + Line: 155 > >> + > >> +3. Excluding required properties, but one is required: > >> + Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml > >> + Line: 91 > >> + > >> +4. Array with numbers (items) from given range - min/max: > >> + Documentation/devicetree/bindings/arm/l2c2x0.yaml > >> + Line: 74 > >> + > >> +5. Array with numbers (items) from given range - enum: > >> + Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml > >> + Line: 101 > >> + > >> +6. Uint32 matrix, variable length of two-items: > >> + Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml > >> + Line: 278 > >> + > >> +7. Phandle to syscon with offset: > >> + Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml > >> + Line: 42 > >> + > >> +8. Variable length of array (e.g. clocks and clock-names) but narrowed to > >> + specific variant: > >> + Documentation/devicetree/bindings/clock/qcom,mmcc.yaml > >> + Lines: 33 and 71 > > > > It seems like some of these that are just a single property we could add > > to example-schema.yaml. > > I am afraid the example-schema will grow too big for folks to look into. > It's already quite complicated, with explanations of the dtschema > behavior itself. How about splitting up the top-level descriptions and property examples? > How about then RST file with small code snippets? Then they don't validate. > > > Also, perhaps a reference to this from writing-schema.rst. > > I can do this as well. > > The problem with my approach above (and adding these to writing-schema) > is that examples above can change, lines can be inadequate. I just meant a link in writing-schema.rst to this doc. We already have that for example-schema.yaml. Rob
