Re: [PATCH] dt-bindings: net: ethernet-phy: clarify when compatible must specify PHY ID

Conor Dooley
2025-10-31T15:08:09Z

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On Fri, Oct 31, 2025 at 02:01:26PM +0100, Andrew Lunn wrote:
> On Fri, Oct 31, 2025 at 09:15:06AM +0100, Buday Csaba wrote:
> > Change PHY ID description in ethernet-phy.yaml to clarify that a
> > PHY ID is required (may -> must) when the PHY requires special
> > initialization sequence.
> >
> > Link: https://lore.kernel.org/netdev/20251026212026.GA2959311-robh@kernel.org/
> > Link: https://lore.kernel.org/netdev/aQIZvDt5gooZSTcp@debianbuilder/
> >
> > Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
> > ---
> > Documentation/devicetree/bindings/net/ethernet-phy.yaml | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > index 2ec2d9fda..6f5599902 100644
> > --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> > @@ -35,9 +35,10 @@ properties:
> > description: PHYs that implement IEEE802.3 clause 45
> > - pattern: "^ethernet-phy-id[a-f0-9]{4}\\.[a-f0-9]{4}$"
> > description:
> > - If the PHY reports an incorrect ID (or none at all) then the
> > - compatible list may contain an entry with the correct PHY ID
> > - in the above form.
> > + If the PHY reports an incorrect ID (or none at all), or the PHY
> > + requires a specific initialization sequence (like a particular
> > + order of clocks, resets, power supplies), then the compatible list
> > + must contain an entry with the correct PHY ID in the above form.
>
> That is good start, but how about:
>
> PHYs contain identification registers. These will be read to
> identify the PHY. If the PHY reports an incorrect ID, or the
> PHY requires a specific initialization sequence (like a
> particular order of clocks, resets, power supplies), in
> order to be able to read the ID registers, then the
> compatible list must contain an entry with the correct PHY
> ID in the above form.
>
> The first two sentences make it clear we ideally use the ID registers.
> Then we say what happens if cannot work.
>
> The "(or none at all)" is exactly the case you are trying to clarify,
> it does not respond due to missing reset, clocks etc. We don't need to
> say it twice, so i removed it.

I like this wording,
Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: changes-requested

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