Re: [PATCH v2 2/4] dt-bindings: iio: dac: add adi,ad5710r.yaml

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 28 Jul 2026 16:41:26 +0100
Conor Dooley <conor@kernel.org> wrote:

> On Fri, Jul 24, 2026 at 10:57:38PM +0100, Jonathan Cameron wrote:
> > On Tue, 21 Jul 2026 16:52:10 +0100
> > Conor Dooley <conor@kernel.org> wrote:
> >   
> > > On Tue, Jul 21, 2026 at 04:47:11PM +0800, Kim Seer Paller wrote:  
> > > > Add device tree bindings for the Analog Devices AD5710R/AD5711R
> > > > 8-channel 12-/16-bit Configurable IDAC/VDAC.
> > > > 
> > > > Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
> > > > ---
> > > >  .../devicetree/bindings/iio/dac/adi,ad5710r.yaml   | 143 +++++++++++++++++++++    
> > >   
> > > > +patternProperties:
> > > > +  "^channel@[0-7]$":
> > > > +    $ref: /schemas/iio/dac/dac.yaml#
> > > > +    type: object
> > > > +    description:
> > > > +      Represents the external channels which are connected to the DAC.
> > > > +
> > > > +    properties:
> > > > +      reg:
> > > > +        description: Channel number
> > > > +        items:
> > > > +          minimum: 0
> > > > +          maximum: 7
> > > > +
> > > > +      adi,ch-func:
> > > > +        description:
> > > > +          Channel output type. Use CH_FUNC_VOLTAGE_OUTPUT for voltage
> > > > +          output or CH_FUNC_CURRENT_OUTPUT for current output.
> > > > +        $ref: /schemas/types.yaml#/definitions/uint32
> > > > +        enum: [1, 2]    
> > > 
> > > Please make this property a string.  
> > 
> > It's an existing binding.  I guess it is generic enough that perhaps we
> > should make it a generic channel property and as part of that we can
> > flip over to a string.  
> 
> Ah, if it is something already established then it can stay as-is.
> 
> > We may need to create a top level channels.yaml to cover both ADC and DAC
> > channels though and reference that from both files.  
> 
> I mean yeah, that was one thought I had originally about the
> spi-device-address property. I'm surprised there's already not more
> commonality to begin with.
> 
> Just how common is some sort of "channel function" property and how
> many devices are bastardising other properties like diff-channel with a
> virtual channel to achieve the same result?

I don't think it is that common to mix different things that can be
read on the same pin beyond a simple ADC / GPIO that we tend to
handle by just not having the ADC channel specified.  Still there
is clearly a non zero number of devices that do.

I can't immediately recall the virtual channel trick you suggest
being used except when it is routing from a different place
in a SoC which to me is a different input via a mux, rather than
mode of the channel. 

Jonathan

> 
> > 
> > I guess we don't need to do that yet though given this is a DAC only device.
> > The original place we added adi,ch-func is a combined ADC / DAC and 
> > has a lot more possible functions.
> > 
> > Jonathan
> > 
> >