linux-kernel - Re: [Patch v3 6/6] dt-bindings: thermal: Add dt binding for QCOM LMh

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Message-ID: <2d11017d-8722-30d1-6b91-214c341e8ab4@linaro.org>
Date:   Mon, 12 Jul 2021 20:54:33 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     agross@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, rjw@...ysocki.net, robh+dt@...nel.org,
        tdas@...eaurora.org, mka@...omium.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [Patch v3 6/6] dt-bindings: thermal: Add dt binding for QCOM LMh



On 7/10/21 12:21 AM, Bjorn Andersson wrote:
> On Thu 08 Jul 07:06 CDT 2021, Thara Gopinath wrote:
> 
>> Add dt binding documentation to describe Qualcomm
>> Limits Management Hardware node.
>>
>> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
>> ---
>>   .../devicetree/bindings/thermal/qcom-lmh.yaml | 100 ++++++++++++++++++
>>   1 file changed, 100 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/thermal/qcom-lmh.yaml b/Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
>> new file mode 100644
>> index 000000000000..7f62bd3d543d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/thermal/qcom-lmh.yaml
>> @@ -0,0 +1,100 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +# Copyright 2021 Linaro Ltd.
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/thermal/qcom-lmh.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Qualcomm Limits Management Hardware(LMh)
>> +
>> +maintainers:
>> +  - Thara Gopinath <thara.gopinath@...aro.org>
>> +
>> +description:
>> +  Limits Management Hardware(LMh) is a hardware infrastructure on some
>> +  Qualcomm SoCs that can enforce temperature and current limits as
>> +  programmed by software for certain IPs like CPU.
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - qcom,sdm845-lmh
>> +
>> +  reg:
>> +    items:
>> +      - description: core registers
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  '#interrupt-cells':
>> +    const: 1
>> +
>> +  interrupt-controller: true
>> +
>> +  qcom,lmh-cpu-id:
>> +    description:
>> +      CPU id of the first cpu in the LMh cluster
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +
>> +  qcom,lmh-temperature-arm:
>> +    description:
>> +      An integer expressing temperature threshold in millicelsius at which
>> +      the LMh thermal FSM is engaged.
> 
> Do we know (by any public source) what "arm", "low" and "high" means
> beyond that they somehow pokes the state machine?

Not from public documentation. I know what these thresholds means, 
atleast to some extent. Though I will never claim to be an expert in 
this! There is an error in description of qcom,lmh-temperature-low and 
qcom,lmh-temperature-high below. I copied
and forgot to change the description. I will fix it.

> 
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +
>> +  qcom,lmh-temperature-low:
>> +    description:
>> +      An integer expressing temperature threshold in millicelsius at which
>> +      the LMh thermal FSM is engaged.
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +
>> +  qcom,lmh-temperature-high:
>> +    description:
>> +      An integer expressing temperature threshold in millicelsius at which
>> +      the LMh thermal FSM is engaged.
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +  - #interrupt-cells
>> +  - interrupt-controller
>> +  - qcom,lmh-cpu-id
>> +  - qcom,lmh-temperature-arm
>> +  - qcom,lmh-temperature-low
>> +  - qcom,lmh-temperature-high
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +    #include <dt-bindings/clock/qcom,rpmh.h>
>> +    #include <dt-bindings/interconnect/qcom,sdm845.h>
> 
> I don't see why you need qcom,rpmh.h or the interconnect include in this
> example.

I could have sworn make dt-bindings check failed. But maybe only The 
first include is needed. I will remove the other two.

> 
>> +
>> +    lmh_cluster1: lmh@...70800 {
>> +      compatible = "qcom,sdm845-lmh";
>> +      reg = <0 0x17d70800 0 0x401>;
> 
> #address- and #size-cells are 1 in the wrapper that validates the
> examples, so drop the two zeros.

Ok.

> 
>> +      interrupts = <GIC_SPI 33 IRQ_TYPE_LEVEL_HIGH>;
>> +      qcom,lmh-cpu-id = <0x4>;
>> +      qcom,lmh-temperature-arm = <65000>;
>> +      qcom,lmh-temperature-low = <94500>;
>> +      qcom,lmh-temperature-high = <95000>;
>> +      interrupt-controller;
>> +      #interrupt-cells = <1>;
>> +    };
>> +  - |
> 
> This is a different example from the one above, if you intended that,
> don't you need the #include of arm-gic.h here as well?

Again make dt-bindings check did not fail. It is a different example.
So I am not sure of the norm here. Is one example good enough ?

> 
> Regards,
> Bjorn
> 
>> +    lmh_cluster0: lmh@...78800 {
>> +      compatible = "qcom,sdm845-lmh";
>> +      reg = <0 0x17d78800 0 0x401>;
>> +      interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
>> +      qcom,lmh-cpu-id = <0x0>;
>> +      qcom,lmh-temperature-arm = <65000>;
>> +      qcom,lmh-temperature-low = <94500>;
>> +      qcom,lmh-temperature-high = <95000>;
>> +      interrupt-controller;
>> +      #interrupt-cells = <1>;
>> +    };
>> +  - |
>> -- 
>> 2.25.1
>>

-- 
Warm Regards
Thara (She/Her/Hers)