[PATCH v6 01/12] dt-bindings: display/msm: split qcom,mdss bindings

[Krzysztof Kozlowski]

On 10/09/2022 00:23, Rob Herring wrote:
>>>>
>>>> This should be ref to dsi-controller-main.yaml... or based on previous
>>>> Rob's feedback you dropped it everywhere in children?
>>>
>>> I don't think I said. I thought about it some, as yes, we normally have
>>> done as you suggested. The downside is with a ref we'll do the whole
>>> validation of the child node twice (unless the referenced schema has a
>>> 'select: false') whereas here only 'compatible' is validated twice. This
>>> way also complicates checking for unevaluatedProperties/additionalProperties.
>>>
>>> So maybe better to keep with the 'normal' way and make this a ref.
>>
>> Well.. I tried using $ref in the previous iteration, but then I faced
>> the fact that I can not use it. Using the $ref the node gets validated
>> even if it is disabled, and we do not want to do this. The nodes are
>> usually split in way that regulators are specified in the board DT file.
>> Thus disabled dsi/dsi-phy nodes do not get all the required regulators.
>> And dt-validate happily dumps tons of warnings for disabled nodes. Thus
>> I ended up with the compatible rather than $ref.
> 
> Only warnings about required properties? Those are supposed to get
> filtered out if the node is disabled. Maybe being in a $ref doesn't
> work.

This seems to break regardless it is in $ref or when you directly
reference the schema.

I tested display/msm/dpu-sc7180.yaml on modified DTB when a required
property is missing (I removed reg-names) and:

1. When node is enabled:

c7180-idp.dtb: display-controller at ae01000: 'reg-names' is a required
property

	Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml

rch/arm64/boot/dts/qcom/sc7180-idp.dtb: display-controller at ae01000:
Unevaluated properties are not allowed ('interrupt-parent',
'interrupts', 'operating-points-v2', 'opp-table', 'ports',
'power-domains' were unexpected)


2. When node is disabled the first error disappears (so no clue which
one is missing) but schema does not pass:

qcom/sc7180-idp.dtb: display-controller at ae01000: Unevaluated properties
are not allowed ('interrupt-parent', 'interrupts',
'operating-points-v2', 'opp-table', 'ports', 'power-domains' were
unexpected)

	From schema: Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml


However I think there is no such problem, as Dmitry said, that ref
changes anything. There will be always failure - either from parent
schema (using $ref) or from device child schema (the one which actually
misses the property).

Best regards,
Krzysztof