On 4/21/24 21:14, Krzysztof Kozlowski wrote:
> On 20/04/2024 18:15, Jan Dakinevich wrote:
>>
>>
>> On 4/20/24 00:09, Rob Herring wrote:
>>> 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@xxxxxxxxxxxxxxxxx>
>>>> ---
>>>>
>>>> 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.
>>
>> Writing a lot of entries don't scary me too much, but the reason is that
>> the existence of optional clock sources depends on schematics. Also, we
>
> Aren't you documenting SoC component, not a board?
Yes, I'm documenting SoC component. And the feature of this component is
that its external clock inputs are not mandatory.
> So how exactly it
> depends on schematics? SoC is done or not done...
>
Schematics determines which external clock sources exist.
>> unable to declare dt-nodes for 'clocks' array in any generic way,
>> because their declaration would depends on that what is actually
>> connected to the SoC (dt-node could be "fixed-clock" with specific rate
>> or something else).
>
> So these are clock inputs to the SoC?
>
Yes, these are clock inputs to the SoC, and external hardware could be
connected to them.
>>
>> By the way, I don't know any example (neither for A1 SoC nor for other
>> Amlogic's SoCs) where these optional clocks are used, but they are
>> allowed by hw.
>>
>> This is my understanding of this controller. I hope, Jerome Brunet will
>> clarify how it actually works.
>
> Best regards,
> Krzysztof
>
--
Best regards
Jan Dakinevich
