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

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Date:   Wed, 26 Oct 2022 13:18:54 +0900
From:   Hector Martin <marcan@...can.st>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "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 26/10/2022 03.56, Krzysztof Kozlowski wrote:
> 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?

Sorry, I didn't understand what you meant. You mean that the two entries
should be merged, with an enum for the first item listing both SoCs, right?

- Hector