Re: [PATCH net-next v3 03/10] dt-bindings: net: cdns,macb: replace cdns,refclk-ext with cdns,refclk-source

Conor Dooley
2026-03-11T18:08:54Z

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On Wed, Mar 11, 2026 at 08:00:54AM +0100, Krzysztof Kozlowski wrote:
> On Tue, Mar 10, 2026 at 05:17:10PM +0000, Conor Dooley wrote:
> > From: Conor Dooley <conor.dooley@microchip.com>
> >
> > Ryan added cdns,refclk-ext with the intent of decoupling the source of
> > the reference clock on sama7g5 (and related platforms) from the
> > compatible. Unfortunately, the default for sama7g5-emac is an external
> > reference clock, so this property had no effect there, so that
> > compatibility with older devicetrees is preserved.
> > Replace cdns,refclk-ext with one that supports both default states and
> > therefore is usable for sama7g5-emac.
> >
> > For now, limit it to only the platforms that have USRIO controlled
> > reference clock selection, but this could be generalised in the future.
> >
> > Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> > ---
> > .../devicetree/bindings/net/cdns,macb.yaml | 39 ++++++++++++++++---
> > 1 file changed, 34 insertions(+), 5 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/net/cdns,macb.yaml b/Documentation/devicetree/bindings/net/cdns,macb.yaml
> > index cb14c35ba9969..a492357570edd 100644
> > --- a/Documentation/devicetree/bindings/net/cdns,macb.yaml
> > +++ b/Documentation/devicetree/bindings/net/cdns,macb.yaml
> > @@ -120,12 +120,14 @@ properties:
> > power-domains:
> > maxItems: 1
> >
> > - cdns,refclk-ext:
> > - type: boolean
>
> This is already an implemented ABI, so you cannot drop it even if some
> devices works fine on default. Instead please deprecate it and keep
> drivers backwards compatible for whoever is using it.

The driver still will support it for those devices, but I don't see any
value in keeping the property about, even deprecated, when it doesn't
work properly. If you insist that it be kept and marked deprecated, it
needs conditional rules to only permit it on devices that it actually
does something. I'm surprised you even considered that I would drop
support for it from the driver!

> > + cdns,refclk-source:
> > + $ref: /schemas/types.yaml#/definitions/string
> > + enum:
> > + - internal
> > + - external
> > description:
> > - This selects if the REFCLK for RMII is provided by an external source.
> > - For RGMII mode this selects if the 125MHz REF clock is provided by an external
> > - source.
> > + Select whether or not the refclk for RGMII or RMII is provided by an
> > + internal or external source. The default is device specific.
>
> Best regards,
> Krzysztof
>

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