linux-kernel - Re: [PATCH 1/3] dt-bindings: hwmon: Add Infineon TDA38640

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Message-ID: <CABqG17iChAyb0gzb2uXfsv5GkiM3a+LoSavdqhjvw3FUccaw8A@mail.gmail.com>
Date:   Tue, 25 Jul 2023 19:47:09 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        krzysztof.kozlowski+dt@...aro.org,
        Conor Dooley <conor+dt@...nel.org>,
        linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: hwmon: Add Infineon TDA38640

Hi Rob,


On Tue, 25 Jul 2023 at 18:40, Rob Herring <robh@...nel.org> wrote:
>
> On Tue, Jul 25, 2023 at 01:40:26PM +0200, Naresh Solanki wrote:
> > From: Patrick Rudolph <patrick.rudolph@...ements.com>
> >
> > The TDA38640 has a bug in SVID mode and to enable a workaround
> > remove the TDA38640 from trivial-devices and add a complete schema.
> >
> > The schema adds the custom property 'infineon,en-pin-fixed-level' to
> > signal a fixed level on the ENABLE pin and to enable the workaround.
> > When the ENABLE pin is left floating it's internally pulled low.
> >
> > If not specified the driver will continue to use the PMBUS_OPERATION
> > register to enable the regulator. When specified the driver will use
> > the PMBUS_ON_OFF_CONFIG register to enable the regulator.
> >
> > Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> > Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> > ---
> >  .../hwmon/pmbus/infineon,tda38640.yaml        | 50 +++++++++++++++++++
> >  .../devicetree/bindings/trivial-devices.yaml  |  2 -
> >  2 files changed, 50 insertions(+), 2 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
> > new file mode 100644
> > index 000000000000..520112e4e271
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
> > @@ -0,0 +1,50 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +
> > +$id: http://devicetree.org/schemas/hwmon/pmbus/infineon,tda38640.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Infineon TDA38640 Synchronous Buck Regulator with SVID and I2C
> > +
> > +description: |
> > +  The Infineon TDA38640 is a 40A Single-voltage Synchronous Buck
> > +  Regulator with SVID and I2C designed for Industrial use.
> > +
> > +  Datasheet: https://www.infineon.com/dgdl/Infineon-TDA38640-0000-DataSheet-v02_04-EN.pdf?fileId=8ac78c8c80027ecd018042f2337f00c9
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - infineon,tda38640
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  infineon,en-pin-fixed-level:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: |
> > +      Fixed level of the ENABLE pin. When specified the PMBUS_ON_OFF_CONFIG
> > +      register is used to enable the regulator instead of the PMBUS_OPERATION
> > +      register to workaround a bug of the tda38640 when operating in SVID-mode.
> > +      If the ENABLE pin is left floating the internal pull-down causes a low
> > +      level on the pin.
>
> Neither this nor the commit message answers how do I decide if I set
> this property or not? How you work-around it is not that relevant to the
> binding.
Sure will update this as:
The property becomes relevant when dealing with the tda38640 in
SVID-mode, providing an alternative method to enable the regulator by
using the PMBUS_ON_OFF_CONFIG register instead of the PMBUS_OPERATION
register

Regards,
Naresh
>
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        tda38640@40 {
> > +            compatible = "infineon,tda38640";
> > +            reg = <0x40>;
> > +        };
> > +    };
> > +
> > diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
> > index 6e24c4d25ec3..2b1fbb2a672b 100644
> > --- a/Documentation/devicetree/bindings/trivial-devices.yaml
> > +++ b/Documentation/devicetree/bindings/trivial-devices.yaml
> > @@ -151,8 +151,6 @@ properties:
> >            - infineon,slb9645tt
> >              # Infineon SLB9673 I2C TPM 2.0
> >            - infineon,slb9673
> > -            # Infineon TDA38640 Voltage Regulator
> > -          - infineon,tda38640
> >              # Infineon TLV493D-A1B6 I2C 3D Magnetic Sensor
> >            - infineon,tlv493d-a1b6
> >              # Infineon Multi-phase Digital VR Controller xdpe11280
> >
> > base-commit: 55612007f16b5d7b1fb83a7b0f5bb686829db7c7
> > --
> > 2.41.0
> >