[RFC PATCH v3 4/6] dt-bindings: clock: meson: document A1 SoC audio clock controller driver

[Rob Herring]

On Fri, Apr 19, 2024 at 03:58:10PM +0300, Jan Dakinevich wrote:
> Add device tree bindings for A1 SoC audio clock and reset controllers.
> 
> Signed-off-by: Jan Dakinevich <jan.dakinevich at salutedevices.com>
> ---
> 
> This controller has 6 mandatory and up to 20 optional clocks. To describe
> this, I use 'additionalItems'. It produces correct processed-schema.json:
> 
>   "clock-names": {
>       "maxItems": 26,
>       "items": [
>           {
>               "const": "pclk"
>           },
>           {
>               "const": "dds_in"
>           },
>           {
>               "const": "fclk_div2"
>           },
>           {
>               "const": "fclk_div3"
>           },
>           {
>               "const": "hifi_pll"
>           },
>           {
>               "const": "xtal"
>           }
>       ],
>       "additionalItems": {
>           "oneOf": [
>               {
>                   "pattern": "^slv_sclk[0-9]$"
>               },
>               {
>                   "pattern": "^slv_lrclk[0-9]$"
>               }
>           ]
>       },
>       "type": "array",
>       "minItems": 6
>   },
> 
> and it behaves as expected. However, the checking is followed by
> complaints like this:
> 
>   Documentation/devicetree/bindings/clock/amlogic,a1-audio-clkc.yaml: properties:clock-names:additionalItems: {'oneOf': [{'pattern': '^slv_sclk[0-9]$'}, {'pattern': '^slv_lrclk[0-9]$'}]} is not of type 'boolean'
> 
> And indeed, 'additionalItems' has boolean type in meta-schema. So, how to
> do it right?

The meta-schemas are written both to prevent nonsense that json-schema 
allows by default (e.g additionalitems (wrong case)) and constraints to 
follow the patterns we expect. I'm happy to loosen the latter case if 
there's really a need. 

Generally, most bindings shouldn't be using 'additionalItems' at all as 
all entries should be defined, but there's a few exceptions. Here, the 
only reasoning I see is 26 entries is a lot to write out, but that 
wouldn't really justify it. As Krzysztof pointed out, you either have 
the clocks in the h/w or you don't, so saying they are variable is 
suspect.

Rob