linux-kernel - Re: [PATCH v1 1/4] dt-bindings: iio: adc: Add MediaTek MT6359 PMIC AUXADC

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Date: Tue, 4 Jun 2024 10:55:55 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, jic23@...nel.org
Cc: lars@...afoo.de, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, matthias.bgg@...il.com, lee@...nel.org,
 andy@...nel.org, nuno.sa@...log.com, bigunclemax@...il.com,
 dlechner@...libre.com, marius.cristea@...rochip.com,
 marcelo.schmitt@...log.com, fr0st61te@...il.com, mitrutzceclan@...il.com,
 mike.looijmans@...ic.nl, marcus.folkesson@...il.com,
 linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v1 1/4] dt-bindings: iio: adc: Add MediaTek MT6359 PMIC
 AUXADC

Il 01/06/24 17:32, Krzysztof Kozlowski ha scritto:
> On 30/05/2024 11:34, AngeloGioacchino Del Regno wrote:
>> Add a new binding for the MT6350 Series (MT6357/8/9) PMIC AUXADC,
>> providing various ADC channels for both internal temperatures and
>> voltages, audio accessory detection (hp/mic/hp+mic and buttons,
>> usually on a 3.5mm jack) other than some basic battery statistics
>> on boards where the battery is managed by this PMIC.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> ---
>>   .../iio/adc/mediatek,mt6359-auxadc.yaml       | 43 +++++++++++++++++++
>>   .../iio/adc/mediatek,mt6357-auxadc.h          | 21 +++++++++
>>   .../iio/adc/mediatek,mt6358-auxadc.h          | 22 ++++++++++
>>   .../iio/adc/mediatek,mt6359-auxadc.h          | 22 ++++++++++
>>   4 files changed, 108 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml
>>   create mode 100644 include/dt-bindings/iio/adc/mediatek,mt6357-auxadc.h
>>   create mode 100644 include/dt-bindings/iio/adc/mediatek,mt6358-auxadc.h
>>   create mode 100644 include/dt-bindings/iio/adc/mediatek,mt6359-auxadc.h
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml b/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml
>> new file mode 100644
>> index 000000000000..dd6c331905cf
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml
>> @@ -0,0 +1,43 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/iio/adc/mediatek,mt6359-auxadc.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: MediaTek MT6350 series PMIC AUXADC
>> +
>> +maintainers:
>> +  - AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> +
>> +description:
>> +  The Auxiliary Analog/Digital Converter (AUXADC) is an ADC found
>> +  in some MediaTek PMICs, performing various PMIC related measurements
>> +  such as battery and PMIC internal voltage regulators temperatures,
>> +  accessory detection resistance (usually, for a 3.5mm audio jack)
>> +  other than voltages for various PMIC internal components.
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - mediatek,mt6357-auxadc
>> +      - mediatek,mt6358-auxadc
>> +      - mediatek,mt6359-auxadc
>> +
>> +  "#io-channel-cells":
>> +    const: 1
>> +
>> +additionalProperties: false
> 
> If there is going to be a re-spin, please move this below required: block.
> 

Yep, will do. Fixed up for v2.

>> +
>> +required:
>> +  - compatible
>> +  - "#io-channel-cells"
>> +
>> +examples:
>> +  - |
>> +    pmic {
>> +        pmic_adc: adc {
>> +            compatible = "mediatek,mt6359-auxadc";
>> +            #io-channel-cells = <1>;
>> +        };
> 
> This suggests that you should grow (make complete) the parent PMIC example.

Uhm, should I instead add that to bindings/mfd/mediatek,mt6357.yaml and avoid
growing the parent example?

   adc:
     type: object
     $ref: /schemas/iio/adc/mediatek,mt6359-auxadc.yaml
     unevaluatedProperties: false

> 
> Actually having this as a separate node is not really needed. Why it
> cannot be just part of the MFD/parent node?
> 

(glossary: PWRAP = PMIC [SPI] WRAPper)

The top node is the PWRAP, an IP that is (mostly) used to dispatch commands to
the PMIC, but the AUXADC is not integrated into the PWRAP, but into the PMIC.

Declaring the AUXADC as a PWRAP child would therefore be an incorrect description
of the hardware.

P.S.: not necessary, but to "complete the circle" ... note that the PWRAP can be
       skipped on some SoCs/firmwares/configurations, even though afaik that's only
       mostly for debugging purposes, it's not granted that you have pwrap between
       SoC and PMIC on all SoCs/fws/confs, even though, all of the boards that are
       supported upstream do have it and do require it.

Cheers,
Angelo

> 
> Best regards,
> Krzysztof
>