linux-kernel - Re: [PATCH v2 2/2] dt-bindings: hwmon/pmbus: Add Infineon TDA38740A

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Message-ID: <7bf30b16-c98e-4c18-816c-58f632fcf939@kernel.org>
Date: Wed, 7 Jan 2026 17:14:53 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: ASHISH YADAV <ashishyadav78@...il.com>, Guenter Roeck
 <linux@...ck-us.net>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, ASHISH YADAV <Ashish.Yadav@...ineon.com>
Subject: Re: [PATCH v2 2/2] dt-bindings: hwmon/pmbus: Add Infineon TDA38740A

On 07/01/2026 15:45, ASHISH YADAV wrote:
> Document the TDA38740A/25A device tree binding.
> 
> Signed-off-by: ASHISH YADAV <Ashish.Yadav@...ineon.com>
> 
> ---
> Changes in v2:
>  - Review comments address:

You need to write here what you exactly changed.


> https://lore.kernel.org/all/2ee75453-0869-4348-ad92-f7ff71aca75d@kernel.org/
> 
> Driver code in review process:
> https://www.spinics.net/lists/kernel/msg5985470.html
> ---
>  .../hwmon/pmbus/infineon,tda38740a.yaml       | 81 +++++++++++++++++++
>  1 file changed, 81 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38740a.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38740a.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38740a.yaml
> new file mode 100644
> index 000000000000..cd4102350a15
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38740a.yaml
> @@ -0,0 +1,81 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +
> +$id: http://devicetree.org/schemas/hwmon/pmbus/infineon,tda38740a.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Infineon TDA38740A and TDA38725A Synchronous Buck Regulator with I2C
> +
> +maintainers:
> +  - ASHISH YADAV <Ashish.Yadav@...ineon.com>
> +
> +description: |
> +  The Infineon TDA38740A/TDA38725A is a 40A/25A Single-voltage Synchronous
> +  Buck Regulator with I2C designed for Industrial use.
> +
> +  Datasheet:
> +  https://www.infineon.com/assets/row/public/documents/24/49/infineon-tda38740a-tda38725a-datasheet-en.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - infineon,tda38725a
> +      - infineon,tda38740a
> +
> +  reg:
> +    maxItems: 1
> +
> +  infineon,vout-voltage-multiplier:

vout of what? Of input supply? But there is no input supply... Maybe you
just want to set output regulator supply?


> +    description: |
> +      TDA38740/25 pin strap parts are available in two flavors of 1:1 & 1:2
> +      vout scale loop.
> +      For the 1:1 vout_scale_loop version, there is no need for any resistor
> +      divider as output voltage sense pins are directly connected to
> +      the output.
> +
> +      For a 1:2 scale loop version, it is recommended to use 499 ohms each for
> +      top and bottom across the feedback path.
> +      However, in some applications customers tend to use an intentional
> +      resistor divider across the output with a different divider ratio other
> +      than 1:1 or 1:2 to alter the actual output voltage.
> +
> +      For example, if pin strap part is set to Vboot of 0.7V,they use a
> +      resistor divider to generate 0.75V using the equation provided in
> +      Section 13.3 of the datasheet.In this case, as there are only two
> +      vout_scale_loop options of 1:1 and 1:2 that the IC can identify,
> +      Read_Vout would still read as 0.7V in the telemetry and the baseboard
> +      management controllers would use this telemetry data to monitor the
> +      rail parameters leading to false tripping of the system.
> +      This multiplier is used to offset the telemetry output voltage Read_Vout
> +      so that the telemetry data is reported correctly to the monitoring
> +      controller,in this example the multiplier would be 0.75/0.7 = 1.071.
> +
> +      This multiplier is required only for any external monitoring of the rail
> +      output voltage. All the other Vout related parameters are used
> +      internally by the IC and there is only a slight impact on the fault
> +      thresholds.The impact can be calculated using equations in Section 13.3
> +      of the datasheet.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 2
> +    maxItems: 2
> +


So this was a regulator before, now it is not. Confusing... Parts of the
description are saying this is regulator, so you miss regulator.yaml
reference in top-level. Anyway, I am not doing full review with such
incomplete changelog.


Best regards,
Krzysztof