Re: [PATCH v2 2/3] dt-bindings: dp83867: add binding for output-impedance

[Andrew Lunn <andrew@lunn.ch>]

On Thu, Aug 27, 2026 at 10:04:07AM +0200, Steffen Trumtrar wrote:
> On 2026-08-26 at 17:01 +01, Conor Dooley <conor@kernel.org> wrote:
> 
> > On Wed, Aug 26, 2026 at 02:48:40PM +0200, Steffen Trumtrar wrote:
> > > Currently, the output-impedance can only be set to default, minimum or
> > > maximum or via a nvmem cell.
> > > In cases where there is no backend for a nvmem cell, a value can not be
> > > set.
> > > > Add a DT binding, 'ti,output-impedance-ohms', for specifying the
> > > output-impedance via a fixed value. The existing boolean values for
> > > minimum and maximum still take precedence over the new value.
> > > > Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> > > ---
> > >  Documentation/devicetree/bindings/net/ti,dp83867.yaml | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > > > diff --git a/Documentation/devicetree/bindings/net/ti,dp83867.yaml
> > b/Documentation/devicetree/bindings/net/ti,dp83867.yaml
> > > index 7a6fe516bab27..49fafe3ce6f47 100644
> > > --- a/Documentation/devicetree/bindings/net/ti,dp83867.yaml
> > > +++ b/Documentation/devicetree/bindings/net/ti,dp83867.yaml
> > > @@ -38,6 +38,16 @@ properties:
> > >      items:
> > >        - const: io_impedance_ctrl
> > >  > +  ti,output-impedance-ohms:
> > > +    description: |
> > > +      MAC Interface Impedance control to set the programmable output impedance.
> > > +      Valid range is 0x00 to 0x1f (32 steps).
> > > +      - 0x1f = 35 ohms (minimum impedance)
> > > +      - 0x00 = 70 ohms (maximum impedance)
> > > +      - Step size varies with process.
> > > +    minimum: 0
> > > +    maximum: 31
> > 
> > Your property is named in ohms, but not implemented in ohms.
> 
> So without the -ohms?

No. DT uses real unit, Ohms, Meters, Volts, Degrees Centigrade, Seconds
etc.

Have the driver do the conversion from Ohms to the magical register
value.

	Andrew