linux-kernel - Re: [PATCH v3 2/5] dt-bindings: cpufreq: apple,soc-cpufreq: Add binding for Apple SoC cpufreq

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Message-ID: <21602556-8312-fb7a-1981-cd03a314d904@linaro.org>
Date:   Tue, 25 Oct 2022 14:56:48 -0400
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Hector Martin <marcan@...can.st>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>, asahi@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/5] dt-bindings: cpufreq: apple,soc-cpufreq: Add
 binding for Apple SoC cpufreq

On 25/10/2022 13:22, Hector Martin wrote:
> On 26/10/2022 01.01, Krzysztof Kozlowski wrote:
>> On 24/10/2022 00:39, Hector Martin wrote:
>>> This binding represents the cpufreq/DVFS hardware present in Apple SoCs.
>>> The hardware has an independent controller per CPU cluster, and we
>>> represent them as unique nodes in order to accurately describe the
>>> hardware. The driver is responsible for binding them as a single cpufreq
>>> device (in the Linux cpufreq model).
>>>
>>> Signed-off-by: Hector Martin <marcan@...can.st>
>>> ---
>>>  .../cpufreq/apple,cluster-cpufreq.yaml        | 119 ++++++++++++++++++
>>>  1 file changed, 119 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml b/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
>>> new file mode 100644
>>> index 000000000000..b11452f91468
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/cpufreq/apple,cluster-cpufreq.yaml
>>> @@ -0,0 +1,119 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/cpufreq/apple,cluster-cpufreq.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: Apple SoC cluster cpufreq device
>>
>> Few nits, in general looks fine to me.
>>
>>> +
>>> +maintainers:
>>> +  - Hector Martin <marcan@...can.st>
>>> +
>>> +description: |
>>> +  Apple SoCs (e.g. M1) have a per-cpu-cluster DVFS controller that is part of
>>> +  the cluster management register block. This binding uses the standard
>>> +  operating-points-v2 table to define the CPU performance states, with the
>>> +  opp-level property specifying the hardware p-state index for that level.
>>> +
>>> +properties:
>>> +  compatible:
>>> +    oneOf:
>>> +      - items:
>>> +          - const: apple,t8103-cluster-cpufreq
>>> +          - const: apple,cluster-cpufreq
>>> +      - items:
>>> +          - const: apple,t6000-cluster-cpufreq
>>> +          - const: apple,t8103-cluster-cpufreq
>>> +          - const: apple,cluster-cpufreq
>>> +      - items:
>>> +          - const: apple,t8112-cluster-cpufreq
>>
>> With the first one (t8103) - it's an enum.
> 
> This is deliberate. t6000 is compatible with t8103, but t8112 is not
> (though all are compatible with what the generic apple,cluster-cpufreq
> compatible implies).

I was not talking about t6000. I was talking about two entries - first
and last - which should be just an enum. There is no compatibility, so
what is here deliberate? To not make enum things which are an enum?

Best regards,
Krzysztof