linux-kernel - Re: [PATCH v2 2/3] dt-bindings: hwmon: Add binding for max6639

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Message-ID: <2e3c55a0-256d-f318-a983-17ad3f8e8909@roeck-us.net>
Date:   Tue, 11 Oct 2022 09:54:49 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Naresh Solanki <naresh.solanki@...ements.com>,
        devicetree@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Roland Stigge <stigge@...com.de>
Cc:     linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Marcello Sylvester Bauer <sylv@...v.io>
Subject: Re: [PATCH v2 2/3] dt-bindings: hwmon: Add binding for max6639

On 10/11/22 09:28, Krzysztof Kozlowski wrote:
> On 11/10/2022 06:47, Naresh Solanki wrote:
>> From: Marcello Sylvester Bauer <sylv@...v.io>
>>
>> Add Devicetree binding documentation for Maxim MAX6639 temperature
>> monitor with PWM fan-speed controller.
>>
>> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>> ---
>>   .../bindings/hwmon/maxim,max6639.yaml         | 116 ++++++++++++++++++
>>   1 file changed, 116 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
>> new file mode 100644
>> index 000000000000..bbefb0a57ab3
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
>> @@ -0,0 +1,116 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +
>> +$id: http://devicetree.org/schemas/hwmon/maxim,max6639.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Maxim max6639
>> +
>> +maintainers:
>> +  - Roland Stigge <stigge@...com.de>
>> +
>> +description: |
>> +  The MAX6639 is a 2-channel temperature monitor with dual, automatic, PWM
>> +  fan-speed controller.  It monitors its own temperature and one external
>> +  diode-connected transistor or the temperatures of two external diode-connected
>> +  transistors, typically available in CPUs, FPGAs, or GPUs.
>> +
>> +  Datasheets:
>> +    https://datasheets.maximintegrated.com/en/ds/MAX6639-MAX6639F.pdf
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - maxim,max6639
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  '#address-cells':
>> +    const: 1
>> +
>> +  '#size-cells':
>> +    const: 0
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
>> +patternProperties:
>> +  "^ot[0-1]_indication$":
> 
> No underscores in names.
> 
>> +    type: boolean
>> +    default: false
>> +    description:
>> +      If true then enable OT pin indication.
> 
> Description copies the name of property. Not really useful. Describe
> that it does.
> 
> Why this has 0 and 1 numbers? Isn't it connected with fan?
> 

I had to look up the suggested code to understand what it means.
All the _indication properties actually configure the chip
to enable or disable various alarm output pins (ALERT, OT,
THERM, and FANFAIL). I for my part find the therm "indication"
quite confusing.

Guenter

>> +
>> +  "^therm[0-1]_indication$":
>> +    type: boolean
>> +    default: false
>> +    description:
>> +      If true then enable THERM pin indication.
> 
> Ditto
> 
>> +
>> +  "^fan@[0-1]$":
> 
> [01]
> The same in other cases.
> 
>> +    type: object
>> +    description: |
>> +      Represents the two fans and their specific configuration.
>> +
>> +    $ref: fan-common.yaml#
>> +
>> +    properties:
>> +      reg:
>> +        description: |
>> +          The fan number.
>> +        items:
>> +          minimum: 0
>> +          maximum: 1
>> +
>> +      maxim,fan-spin-up:
>> +        type: boolean
>> +        description:
>> +          If true then whnever the fan starts up from zero drive, it
> 
> whenever
> run spell-check
> 
>> +          is driven with 100% duty cycle for 2s to ensure that it
>> +          starts.
>> +
>> +      maxim,full-speed-on-therm:
>> +        type: boolean
>> +        description:
>> +          If true then force fan to full speed if THERM pin goes low.
>> +
>> +      maxim,fanfail_indication:
> 
> No underscores
> 
>> +        type: boolean
>> +        description:
>> +          If true then enable fanfail pin indication.
> 
> Missing blank line
> 
>> +    required:
>> +      - reg
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    i2c {
>> +      #address-cells = <1>;
>> +      #size-cells = <0>;
>> +
>> +      max6639@10 {
> 
> Node names should be generic.
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> 
>> +        compatible = "maxim,max6639";
>> +        reg = <0x10>;
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        fan@0 {
>> +          reg = <0x0>;
>> +          pulses-per-revolution = <2>;
>> +          max-rpm = <4000>;
>> +          pwm-frequency = <25000>;
>> +        };
>> +
>> +        fan@1 {
>> +          reg = <0x1>;
>> +          pulses-per-revolution = <2>;
>> +          max-rpm = <32000>;
>> +          pwm-frequency = <25000>;
>> +        };
>> +      };
>> +    };
>> +...
> 
> Best regards,
> Krzysztof
>