linux-kernel - Re: [PATCH v3 1/2] dt-bindings: iio: adc: add AD4130

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Message-ID: <Ymm4lJxumCPQKIhB@robh.at.kernel.org>
Date:   Wed, 27 Apr 2022 16:41:40 -0500
From:   Rob Herring <robh@...nel.org>
To:     Cosmin Tanislav <demonsingur@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-iio@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Cosmin Tanislav <cosmin.tanislav@...log.com>
Subject: Re: [PATCH v3 1/2] dt-bindings: iio: adc: add AD4130

On Wed, Apr 27, 2022 at 03:47:13PM +0300, Cosmin Tanislav wrote:
> 
> 
> On 4/26/22 03:37, Rob Herring wrote:
> > On Tue, Apr 19, 2022 at 06:08:27PM +0300, Cosmin Tanislav wrote:
> > > AD4130-8 is an ultra-low power, high precision, measurement solution for
> > > low bandwidth battery operated applications.
> > > 
> > > The fully integrated AFE (Analog Front-End) includes a multiplexer for up
> > > to 16 single-ended or 8 differential inputs, PGA (Programmable Gain
> > > Amplifier), 24-bit Sigma-Delta ADC, on-chip reference and oscillator,
> > > selectable filter options, smart sequencer, sensor biasing and excitation
> > > options, diagnostics, and a FIFO buffer.
> > > 
> > > Signed-off-by: Cosmin Tanislav <cosmin.tanislav@...log.com>
> > > ---
> > >   .../bindings/iio/adc/adi,ad4130.yaml          | 264 ++++++++++++++++++
> > >   1 file changed, 264 insertions(+)
> > >   create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
> > > new file mode 100644
> > > index 000000000000..32996b62cd20
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
> > > @@ -0,0 +1,264 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +# Copyright 2022 Analog Devices Inc.
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/iio/adc/adi,ad4130.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Analog Devices AD4130 ADC device driver
> > > +
> > > +maintainers:
> > > +  - Cosmin Tanislav <cosmin.tanislav@...log.com>
> > > +
> > > +description: |
> > > +  Bindings for the Analog Devices AD4130 ADC. Datasheet can be found here:
> > > +    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4130-8.pdf
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - adi,ad4130-8-16-lfcsp
> > > +      - adi,ad4130-8-16-wlcsp
> > > +      - adi,ad4130-8-24-lfcsp
> > > +      - adi,ad4130-8-24-wlcsp
> > 
> > What is lfcsp? wlcsp seems to be the package type which generally
> > shouldn't be part of the compatible.
> 
> lfcsp is a different package type. Sadly, lfcsp provides less interrupt
> options. On lfcsp, dout-int inside interrupt-names actually only means
> DOUT, while on wlcsp, it means INT. This is why we need to distinguish
> between the different package types. I can't think of any way around it,
> see my reply to Nathan for V1.
> 
> dout support is not implemented in the driver right now because when the
> interrupt pin is configured as dout, FIFO interrupts are unsupported, so
> the entire buffered part of the driver is useless, and extra logic is
> needed for IRQ detection then.

Please capture all this in the binding. At least enough I don't ask the 
same question again when I've forgotten about this.

Rob