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

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Message-ID: <CAJKbuCY=Q2d5sFigb_wTPTKzqpeHX4c5f704YFCqKhsKE32YpA@mail.gmail.com>
Date: Thu, 8 Jan 2026 14:54:10 +0530
From: ashish yadav <ashishyadav78@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Guenter Roeck <linux@...ck-us.net>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 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

Hi Krzysztof,

Please find my response inline.

Thanks a lot for your time and feedback.

With Best Regards
  Ashish Yadav

On Wed, Jan 7, 2026 at 9:44 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> 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.
Sure,I will take care this in v3 version.
>
> > 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?

 Yes, output of 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.
>
Sorry for the inconvenience.
Regulator part is taken out as per review comments from:
https://lore.kernel.org/all/2ee75453-0869-4348-ad92-f7ff71aca75d@kernel.org/


>
> Best regards,
> Krzysztof