linux-kernel - Re: [PATCH v2] dt-bindings: mailbox: add Versal IPI bindings

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Message-ID: <daa14201-2027-4732-bbea-acbb2675e4b8@linaro.org>
Date:   Wed, 13 Dec 2023 17:21:36 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Tanmay Shah <tanmay.shah@....com>, jassisinghbrar@...il.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, michal.simek@....com,
        shubhrajyoti.datta@....com
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        "Levinsky, Ben" <ben.levinsky@....com>
Subject: Re: [PATCH v2] dt-bindings: mailbox: add Versal IPI bindings

On 13/12/2023 17:18, Tanmay Shah wrote:


>>> +    minItems: 1
>>> +    maxItems: 2
>>
>> I don't understand why this change is here. Previously you did not have
>> MMIO address space? If yes, then where do you restrict the old device to
>> disallow these?
> 
> 
> Hardware description is different between ZynqMP and Versal. And so, we have to design
> 
> new bindings for Versal. reg and reg-names for parent node, is only available for new devices.
> 
> The new device is checked with compatible string after "required" section.

Hm? What does that mean?

> 
> Should I add "unevaluatedProperties: false" after "additionalProperties: false" for parent node below [1] ?

No, you should disallow reg/reg-names for older device.

...

> 
>>> +        then:
>>> +          properties:
>>> +            reg:
>>> +              items:
>>> +                - description: Host agent request message buffer
>>> +                - description: Host agent response message buffer
>>> +                - description: Remote agent request message buffer
>>> +                - description: Remote agent response message buffer
>>> +
>>> +            reg-names:
>>> +              items:
>>> +                - const: local_request_region
>>> +                - const: local_response_region
>>> +                - const: remote_request_region
>>> +                - const: remote_response_region
>>> +        else:
>>> +          properties:
>>> +            reg:
>>> +              minItems: 1
>>> +              items:
>>> +                - description: Remote IPI agent control register
>>> +                - description: Remote IPI agent optional message buffer
>>
>> Were these described in old binding? If not, it's a separate change.
> 
> Okay, so I will split this in two patches:
> 
> 1) Clean up current bindings (like remove redundant descriptino, sort "required" property order etc..)

If you want to combine cleanup and functional changes, then this would
be two patches.

> 
> 2) Add versal platforms bindings doc. (This will add if else cases and Versal platform support)

> 
> 
>>> +
>>> +            reg-names:
>>> +              minItems: 1
>>> +              items:
>>> +                - const: ctrl
>>> +                - const: msg
>>
>> Blank line
>>
>>>  required:
>>>    - compatible
>>> -  - interrupts
>>>    - '#address-cells'
>>>    - '#size-cells'
>>> +  - interrupts
>>
>> Separate change with its own rationale. Trivial cleanups can be
>> organized in one patch, but should not be mixed with adding new devices.
> 
> Ack
> 
> 
>>>    - xlnx,ipi-id
>>>  
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            enum:
>>> +              - xlnx,versal-ipi-mailbox
>>> +    then:
>>> +      properties:
>>> +        reg:
>>> +          items:
>>> +            - description: Host IPI agent control registers
>>> +            - description: Host IPI agent optional message buffers
>>> +
>>> +        reg-names:
>>> +          items:
>>> +            - const: ctrl
>>> +            - const: msg
>>> +
>>> +      required:
>>> +        - reg
>>> +        - reg-names
>>> +
>>> +additionalProperties: false
> 
> [1] Here, if I add unevaluatedProperties: false then is it enough for old device to disallow

No, you need reg:false

Best regards,
Krzysztof