Re: [PATCH net-next v4 1/3] dt-bindings: net: ethernet-phy: add property tx-amplitude-100base-tx-percent

[Dimitri Fedrau]

Am Wed, Feb 12, 2025 at 02:04:02PM +0100 schrieb Andrew Lunn:
> On Tue, Feb 11, 2025 at 09:33:47AM +0100, Dimitri Fedrau via B4 Relay wrote:
> > From: Dimitri Fedrau <dimitri.fedrau@xxxxxxxxxxxx>
> > 
> > Add property tx-amplitude-100base-tx-percent in the device tree bindings
> > for configuring the tx amplitude of 100BASE-TX PHYs. Modifying it can be
> > necessary to compensate losses on the PCB and connector, so the voltages
> > measured on the RJ45 pins are conforming.
> > 
> > Signed-off-by: Dimitri Fedrau <dimitri.fedrau@xxxxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/net/ethernet-phy.yaml | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > index 2c71454ae8e362e7032e44712949e12da6826070..e0c001f1690c1eb9b0386438f2d5558fd8c94eca 100644
> > --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > @@ -232,6 +232,12 @@ properties:
> >        PHY's that have configurable TX internal delays. If this property is
> >        present then the PHY applies the TX delay.
> >  
> > +  tx-amplitude-100base-tx-percent:
> > +    description:
> > +      Transmit amplitude gain applied for 100BASE-TX. When omitted, the PHYs
> > +      default will be left as is.
> > +    default: 100
> 
> Doesn't having a default statement contradict the text? Maybe the
> bootloader has set it to 110%, the text suggests it will be left at
> that, but the default value of 100 means it will get set back to 100%?
>
You are right, will remove the default statement.

> What do your driver changes actually do?

Only if tx-amplitude-100base-tx-percent is present, the amplitude should
be changed.

Best regards,
Dimitri Fedrau