linux-kernel - RE: [PATCH v2 3/4] dt-bindings: iio: dac: Add adi,ad3530r.yaml

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Message-ID:
 <PH0PR03MB71417CFD279F01382D025848F9AD2@PH0PR03MB7141.namprd03.prod.outlook.com>
Date: Mon, 31 Mar 2025 01:31:10 +0000
From: "Paller, Kim Seer" <KimSeer.Paller@...log.com>
To: Jonathan Cameron <jic23@...nel.org>
CC: Lars-Peter Clausen <lars@...afoo.de>,
        "Hennerich, Michael"
	<Michael.Hennerich@...log.com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof
 Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v2 3/4] dt-bindings: iio: dac: Add adi,ad3530r.yaml



> -----Original Message-----
> From: Jonathan Cameron <jic23@...nel.org>
> Sent: Friday, March 28, 2025 5:04 PM
> To: Paller, Kim Seer <KimSeer.Paller@...log.com>
> Cc: Lars-Peter Clausen <lars@...afoo.de>; Hennerich, Michael
> <Michael.Hennerich@...log.com>; Rob Herring <robh@...nel.org>; Krzysztof
> Kozlowski <krzk+dt@...nel.org>; Conor Dooley <conor+dt@...nel.org>; linux-
> iio@...r.kernel.org; linux-kernel@...r.kernel.org; devicetree@...r.kernel.org
> Subject: Re: [PATCH v2 3/4] dt-bindings: iio: dac: Add adi,ad3530r.yaml
> 
> [External]
> 
> On Mon, 24 Mar 2025 19:22:57 +0800
> Kim Seer Paller <kimseer.paller@...log.com> wrote:
> 
> > Document the AD3530R/AD3530, an 8-Channel, 16-bit Voltage Output DAC,
> > while the AD3531R/AD3531 is a 4-Channel, 16-Bit Voltage Output DAC.
> > These devices include software-programmable gain controls that provide
> > full-scale output spans of 2.5V or 5V for reference voltages of 2.5V.
> > They operate from a single supply voltage range of 2.7V to 5.5V and are
> > guaranteed to be monotonic by design. Additionally, these devices
> > features a 2.5V, 5ppm/°C internal reference, which is disabled by default.
> >
> > Signed-off-by: Kim Seer Paller <kimseer.paller@...log.com>
> > ---
> >  .../devicetree/bindings/iio/dac/adi,ad3530r.yaml   | 91
> ++++++++++++++++++++++
> >  MAINTAINERS                                        |  1 +
> >  2 files changed, 92 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad3530r.yaml
> b/Documentation/devicetree/bindings/iio/dac/adi,ad3530r.yaml
> > new file mode 100644
> > index
> 0000000000000000000000000000000000000000..e581472b50048bedda742
> 2748035423b9b020382
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad3530r.yaml
> > @@ -0,0 +1,91 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id:
> https://urldefense.com/v3/__http://devicetree.org/schemas/iio/dac/adi,ad353
> 0r.yaml*__;Iw!!A3Ni8CS0y2Y!-bEqh-bKz-a-
> ZzfbJZwXi9KWwKlsk_Pcaj5XQLeLaDBpO8MaryRedRHaL0GUFfNz35tDsFaJkV45P
> fyEzA$
> > +$schema: https://urldefense.com/v3/__http://devicetree.org/meta-
> schemas/core.yaml*__;Iw!!A3Ni8CS0y2Y!-bEqh-bKz-a-
> ZzfbJZwXi9KWwKlsk_Pcaj5XQLeLaDBpO8MaryRedRHaL0GUFfNz35tDsFaJkV5zI4
> zMaQ$
> > +
> > +title: Analog Devices AD3530R and Similar DACs
> > +
> > +maintainers:
> > +  - Kim Seer Paller <kimseer.paller@...log.com>
> > +
> > +description: |
> > +  The AD3530/AD3530R are low power, 8-channel, 16-bit, buffered voltage
> output,
> > +  digital-to-analog converters (DACs) that include software-programmable
> gain
> > +  controls that result in full-scale output spans of 2.5V or 5V for reference
> > +  voltages of 2.5V. The devices operate from single, 2.7V to 5.5V supply
> ranges
> > +  and are guaranteed monotonic by design. The AD3530R also offers a 2.5V,
> > +  5ppm/°C internal reference that is disabled by default.
> > +  Datasheet can be found here:
> > +  https://www.analog.com/media/en/technical-documentation/data-
> sheets/ad3530_ad530r.pdf
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - adi,ad3530r
> 
> You mention this one as well as a variant without the r postfix in the
> 'description'.
> So why not compatible for that?  If it's software compatible with the r version
> than
> a fallback compatible makes sense.  We probably still want to have separate
> compatibles though in case we get an errata that only applies to one of them.
> 
> If they are the same silicon, perhaps with different ratings then make that clear
> in the description and perhaps it is fine to not have both compatibles listed.

The main difference is that the r variant supports both internal and external references,
while the non-r variant supports only external references. I agree with having separate
compatibles. Well, I'm thinking of adding a parameter in chip_info into the driver to
identify internal reference support. What do you think?

> 
> > +      - adi,ad3531r
> 
> This isn't mentioned in the description text.
> 
> > +
> > +  reg:
> > +    maxItems: 1
> 
> Thanks,
> 
> Jonathan