linux-kernel - Re: [PATCH v4 1/2] dt-bindings: remoteproc: mediatek: Make l1tcm reg exclusive to mt819x

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Date:   Wed, 11 May 2022 11:12:45 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, kernel@...labora.com,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Tinghan Shen <tinghan.shen@...iatek.com>,
        Tzung-Bi Shih <tzungbi@...gle.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        linux-remoteproc@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: remoteproc: mediatek: Make l1tcm reg
 exclusive to mt819x

On 10/05/2022 18:50, Nícolas F. R. A. Prado wrote:
>>> Also I had to add a description to the global reg-names, since it
>>> couldn't be neither missing nor empty.
>>
>> It is possible:
>> https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/example-schema.yaml#L91
>>
>> Keep constraints and list of names in properties. Then in allOf:if:then
>> raise minItems or lower maxItems, depending on the variant.
> 
> Hi Krzysztof,
> 
> that example only shows setting minItems to override the default value, but the
> issue here is that it's not possible to override minItems/maxItems (after
> they're already set, even if implicitly) with a different value in the if.

No, this example shows exactly what you need in first step - make one
item on the list optional.

There are several other examples for the entire picture or different
aproach:
https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/example-schema.yaml#L91

https://elixir.bootlin.com/linux/v5.18-rc2/source/Documentation/devicetree/bindings/clock/samsung,exynos7885-clock.yaml#L53

> 
> That is:
> 
> 	properties:
> 	  reg-names:
> 	    items:
> 	      - const: sram
> 	      - const: cfg
> 	      - const: l1tcm

You did not use the example I gave you. Where is the minItems?

> 
> 	if:
> 	  properties:
> 	    compatible:
> 	      enum:
> 		- mediatek,mt8183-scp
> 		- mediatek,mt8186-scp
> 	then:
> 	  properties:
> 	    reg-names:
> 	      minItems: 2
> 	      maxItems: 2
> 
> Generates the error on dtbs_check:
> 
> /home/nfraprado/ext/git/linux/arch/arm64/boot/dts/mediatek/mt8183-kukui-kakadu.dtb: scp@...00000: reg-names: ['sram', 'cfg'] is too short

Missing minItems in first properties.

> 
> I believe the tooling is implicitly adding
> 
> 	      minItems: 3
> 	      maxItems: 3
> 
> to the common reg-names, and since it's not possible to override them, the
> override to 2 doesn't work so they are kept at 3, causing the error.
> 
> Moving the minItems/maxItems to the common reg-names as a test gives:

You cannot just. You need it in both places.

> 
> /home/nfraprado/ext/git/linux/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml: properties:reg-names: {'minItems': 2, 'maxItems': 2, 'items': [{'const': 'sram'}, {'const': 'cfg'}, {'const': 'l1tcm'}]} should not be valid under {'required': ['maxItems']}
> 	hint: "maxItems" is not needed with an "items" list
> 
> That error, plus looking in the items meta-schema, suggests me that maxItems
> isn't supposed to be set lower then the length of items. So even if the
> minItems/maxItems override is fixed, there's still this issue. It seems like
> defining the reg-names list separetely in each if branch is indeed the right way
> to go.



Best regards,
Krzysztof