Re: [PATCH v3 2/3] dt-bindings: iio: light: isl29018: add isil,cover-comp-gain

[me]

On 2026-06-05 15:04, Jonathan Cameron wrote:
> On Thu, 4 Jun 2026 18:01:08 +0100
> Conor Dooley <conor@xxxxxxxxxx> wrote:
>
> > On Thu, Jun 04, 2026 at 12:06:16PM +0200, Herman van Hazendonk wrote:
> > > Document the new optional property that seeds the ISL29018 calibration
> > > scale factor at boot from firmware, allowing boards with tinted cover
> > > glass to ship with correct luminance readings without a userspace helper.
> > >
> > > The value is a positive integer (minimum 1, maximum 65535) that is
> > > multiplied with the raw lux reading.  Userspace can still override it
> > > at runtime through in_illuminance0_calibscale.
> > >
> > > Signed-off-by: Herman van Hazendonk <github.com@xxxxxxxxxx>
> > > ---
> > >  .../devicetree/bindings/iio/light/isl29018.yaml     | 13 +++++++++++++
> > >  1 file changed, 13 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/iio/light/isl29018.yaml b/Documentation/devicetree/bindings/iio/light/isl29018.yaml
> > > index 0ea278b07d1c..92ea2742bbd3 100644
> > > --- a/Documentation/devicetree/bindings/iio/light/isl29018.yaml
> > > +++ b/Documentation/devicetree/bindings/iio/light/isl29018.yaml
> > > @@ -34,6 +34,19 @@ properties:
> > >    vcc-supply:
> > >      description: Regulator that provides power to the sensor
> > >
> > > +  isil,cover-comp-gain:
> > > +    description: |
> > > +      Multiplier applied to the ambient-light reading at startup to
> > > +      compensate for optical loss in the board's cover glass. Boards
> > > +      that mount the sensor under a tinted or coated window typically
> > > +      need a value between a few and a few hundred.
>
> Is it useful to support decimal points on these values?  The userspace 
> interface
> does and you mention the 'right' answer might be only a few which means 
> precision
> at that range will be terrible - less of an issue if 100s!
>
> Thanks
>
> Jonathan
Hard to say, my old HP TouchPad needs 100 as a value here (taken from 
legacy 2.6.35
kernel and binaries). So we probably don't need precision, but I have no 
other
references to substantiate.

Thanks
Herman
> > > The value seeds
> > > +      in_illuminance0_calibscale, so it can still be retuned at
> > > +      runtime through sysfs.
> >
> > Delete this, driver implementation stuff isn't relevant to the
> > devicetree binding.
> >
> > With that gone,
> > Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> >
> > pw-bot: changes-requested
> >
> > Cheers,
> > Conor.
> >
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    minimum: 1
> > > +    maximum: 65535
> > > +    default: 1
> > > +
> > >  required:
> > >    - compatible
> > >    - reg
> > > --
> > > 2.43.0
> > >