devicetree support for compound elements

[pabigot]

I need a devicetree property as described below (documentation detail removed):

  dpd-wakeup-sequence:
    type: compound
    required: false
    description: Specifies wakeup durations for devices without RDPD

with an example use:

dpd-wakeup-sequence = <30000 20 45000>;

The value of this is an array of three integers. binding-template.yaml specifies that compound remains the catch-all for more complex types, but when that's used all the generated macros include deprecation markers.

The documentation separately mentions type: array (which is not a listed available type) which works.

What is the appropriate type to use for this? What would be appropriate if the element types were heterogeneous (what compound used to mean)?

In either case the generation needs to produce the property value as an initializer sequence, rather than individual elements, so some tooling enhancement will be required.

[ulfalizer]

type: array not being documented together with the other types is a (bad) oversight. string and string-array should be explained too.

Will fix tomorrow.

[ulfalizer]

Maybe a length: field could be added to bindings for checking the length too, if needed.

Something like

properties:
    dpd-wakeup-sequence:
        type: array
        length: 3
        required: false

[pabigot]

Yeah, that could be useful, as long as its absence means any number of entries is allowed.

To be clear: array is intended to replace all uses of compound, including heterogenous structures? Or does compound still get used for that. You can answer by making it clear in the PR that improves the documentation.

[pabigot]

Closed by #20173. (The answer to the last question is that array means a list of integer values only. compound appears to be used for "not an array or a phandle-array".)