[PATCH v3] docs: dt-bindings: add DTS Coding Style document

[Krzysztof Kozlowski]

On 29/11/2023 08:29, Francesco Dolcini wrote:
> On Sat, Nov 25, 2023 at 07:44:22PM +0100, Krzysztof Kozlowski wrote:
>> Document preferred coding style for Devicetree sources (DTS and DTSI),
>> to bring consistency among all (sub)architectures and ease in reviews.
> 
> Thank Krzysztof, we had most of this collected as BKM in some internal
> documents and it's great to see the effort to consolidate this and add
> it to the kernel documentation.
> 
>> ---
>> +Following order of properties in device nodes is preferred:
>> +
>> +1. compatible
>> +2. reg
>> +3. ranges
>> +4. Standard/common properties (defined by common bindings, e.g. without
>> +   vendor-prefixes)
>> +5. Vendor-specific properties
>> +6. status (if applicable)
>> +7. Child nodes, where each node is preceded with a blank line
> 
> On point 4, do you have a more explicit way to define what is an actual
> standard/common property? You mention the vendor-prefixes as an example,
> is this just an example or this is the whole definition?

The actual definition is: defined by common bindings, which are:
meta-schemas and schemas in dtschema, and common bindings per subsystem
(e.g. leds/common.yaml).

Lack of vendor-prefix is I think 99% accurate in this matter, but there
are some "linux," ones.

> 
> What would be the order for this for example (from an existing DTS file)?
> 
> 	reg_sdhc1_vmmc: regulator-sdhci1 {
> 		compatible = "regulator-fixed";
> 		pinctrl-names = "default";
> 		pinctrl-0 = <&pinctrl_sd1_pwr_en>;
> 		enable-active-high;
> 		gpio = <&main_gpio0 29 GPIO_ACTIVE_HIGH>;
> 		off-on-delay-us = <100000>;
> 		regulator-max-microvolt = <3300000>;
> 		regulator-min-microvolt = <3300000>;
> 		regulator-name = "+V3.3_SD";
> 		startup-delay-us = <2000>;
> 	};
> 
> I guess the point that is not obvious to me here is where do we want
> pinctrl. I like it at position between 3 and 4, the rationale is that is
> a very frequent property and this way it will be in a similar place for
> every node.


Order here is correct but all of them are generic properties, thus this
coding style does not define ordering within.

Best regards,
Krzysztof