Re: [PATCH 1/2] dt-bindings: iio: dac: add docs for ad8460

David Lechner
2024-05-11T18:47:39Z

On Sat, May 11, 2024 at 11:25 AM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Fri, 10 May 2024 12:28:19 -0500
> David Lechner <dlechner@baylibre.com> wrote:
>
> > On Fri, May 10, 2024 at 1:42 AM Mariel Tinaco <Mariel.Tinaco@analog.com> wrote:
> > >
> > > This adds the bindings documentation for the 14-bit
> > > High Voltage, High Current, Waveform Generator
> > > Digital-to-Analog converter.
> > >
> > > Signed-off-by: Mariel Tinaco <Mariel.Tinaco@analog.com>
> > > ---
> > > .../bindings/iio/dac/adi,ad8460.yaml | 67 +++++++++++++++++++
> > > MAINTAINERS | 7 ++
> > > 2 files changed, 74 insertions(+)
> > > create mode 100644 Documentation/devicetree/bindings/iio/dac/adi,ad8460.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad8460.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad8460.yaml
> > > new file mode 100644
> > > index 000000000..924f76209
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad8460.yaml
> > > @@ -0,0 +1,67 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +# Copyright 2024 Analog Devices Inc.
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/iio/dac/adi,ad8460.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Analog Devices AD8460 DAC
> > > +
> > > +maintainers:
> > > + - Mariel Tinaco <mariel.tinaco@analog.com>
> > > +
> > > +description: |
> > > + Analog Devices AD8460 110 V High Voltage, 1 A High Current,
> > > + Arbitrary Waveform Generator with Integrated 14-Bit High Speed DAC
> > > + https://www.analog.com/media/en/technical-documentation/data-sheets/ad8460.pdf
> > > +
> > > +properties:
> > > + compatible:
> > > + enum:
> > > + - adi,ad8460
> > > +
> > > + reg:
> > > + maxItems: 1
> > > +
> > > + spi-max-frequency:
> > > + maximum: 20000000
> > > +
> > > + vref-supply:
> >
> > It would be nice to make the property name match the pin name since
> > there is more than one reference voltage input.
> >
> > refio-1p2v-supply:
> >
> > > + description: Drive voltage in the range of 1.2V maximum to as low as
> > > + low as 0.12V through the REF_IO pin to adjust full scale output span
> >
> > I don't seen anything in the datasheet named REF_IO. Is this a typo
> > and it should be REFIO_1P2V?
> >
> > > +
> > > + clocks:
> > > + description: The clock for the DAC. This is the sync clock
> > > +
> > > + adi,rset-ohms:
> > > + description: Specify value of external resistor connected to FS_ADJ pin
> > > + to establish internal HVDAC's reference current I_REF
> > > + minimum: 2000
> > > + maximum: 20000
> > > +
> >
> > I see lots more pins on the datasheet, many of which should be trivial
> > to add bindings for (we prefer to have the bindings as complete as
> > possible even if the driver doesn't implement everything). Potential
> > candidates:
> >
> > sdn-reset-gpios: (active high)
> > reset-gpios: (active low)
> > sdn-io-gpios: (active high)
> >
> > hvcc-supply:
> > hvee-supply:
> > vcc-5v-supply:
> > vref-5v-supply:
> > dvdd-3p3v-supply:
> > avdd-3p3v-supply:
> >
> > It also looks like there is a parallel interface for data, so I would
> > expect to see an io-backends property that links to the PHY used for
> > handling that.
> >
> Ultimately yes, but the parallel interface might require some decisions on
> binding that are non obvious until it's actually implemented. So maybe
> don't need that bit from the start. The rest I agree should be here.
>
>

Since the driver patch uses a DMA channel that isn't documented here,
I am assuming that the parallel interface is being used so we do need
to consider it now. :-)