linux-kernel - Re: [PATCH v2 01/12] dt-bindings: net: snps,dwmac: Allow exclusive usage of ahb reset

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Message-ID: <564503dd-b779-4e9f-851d-f34d9ea5fa65@collabora.com>
Date:   Sun, 29 Oct 2023 23:55:58 +0200
From:   Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Samin Guo <samin.guo@...rfivetech.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Richard Cochran <richardcochran@...il.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v2 01/12] dt-bindings: net: snps,dwmac: Allow exclusive
 usage of ahb reset

On 10/29/23 13:21, Krzysztof Kozlowski wrote:
> On 29/10/2023 05:27, Cristian Ciocaltea wrote:
>> The Synopsys DesignWare MAC found on the StarFive JH7100 SoC requires
>> just the 'ahb' reset name, but the binding allows selecting it only in
>> conjunction with 'stmmaceth'.
>>
>> Fix the issue by permitting exclusive usage of the 'ahb' reset name.
>>
>> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
>> ---
>>  Documentation/devicetree/bindings/net/snps,dwmac.yaml | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
>> index 5c2769dc689a..a4d7172ea701 100644
>> --- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
>> +++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
>> @@ -146,7 +146,7 @@ properties:
>>    reset-names:
>>      minItems: 1
>>      items:
>> -      - const: stmmaceth
>> +      - enum: [stmmaceth, ahb]
> 
> Your patch #3 says you have minimum two items. Here you claim you have
> only one reset. It's confusing.

At least the following use-cases need to be supported:

- JH7110: reset-names = "stmmaceth", "ahb";
- JH7110: reset-names = "ahb";
- other:  reset-names = "stmmaceth";

Since this is the schema which gets included later in other bindings,
the property needs to be generic enough to cope with all the above.
[added actual content here for more clarity]

  reset-names:
    minItems: 1
    items:
      - enum: [stmmaceth, ahb]
      - const: ahb

Therefore, only the lower limit (1) is enforced here, while
starfive,jh7110-dwmac.yaml (which PATCH 3 relates to) adds further
constraints (limiting to precisely two items):

    reset-names:
      items:
        - const: stmmaceth
        - const: ahb

I understand the generic binding also allows now specifying 'ahb' twice,
but I'm not sure if there's a convenient way to avoid that (e.g. without
complicating excessively the schema).

Thanks,
Cristian