Re: [PATCH v6 2/7] dt-bindings: net: amlogic,meson-dwmac: add amlogic,t7-dwmac

[Rob Herring <robh@kernel.org>]

On Fri, Nov 13, 2026 at 12:07:55PM +0000, Lucas Tanure wrote:
> On Tue, Nov 10, 2026 at 5:54 PM Rob Herring <robh@kernel.org> wrote:
> >
> > On Thu, Nov 05, 2026 at 10:03:17AM +0000, Lucas Tanure wrote:
> > > The T7 has the same ethernet glue as the G12A but needs two clocks of
> > > its own. The controller reaches memory through a pipeline stage with
> > > its own gate; nothing else claims it, so it is switched off as unused
> > > and transfers never finish. The glue registers sit in a block clocked
> > > together with the MDIO multiplexer, which probes after the controller
> > > has programmed them: the writes are lost and the port keeps the
> > > bootloader's delays.
> > >
> > > So the T7 gets its own clock list, without the timing adjustment clock
> > > it never uses. Its delays follow ethernet-controller.yaml: the PHY adds
> > > the 2ns, and only the receive delay line offers fine tuning, so only
> > > rx-internal-delay-ps is valid here.
> > >
> > > Assisted-by: LLM
> > > Signed-off-by: Lucas Tanure <tanure@linux.com>
> > > ---
> > >  .../bindings/net/amlogic,meson-dwmac.yaml     | 49 +++++++++++++++++++
> > >  1 file changed, 49 insertions(+)
> >
> > I tend to agree with the sashiko comment, but am fine either way. Once
> > the if/then schemas are longer than the main schema, it's a sign to
> > split.
> 
> In V7 I will split as I think it will be easier to review.
> 
> >
> > >
> > > diff --git a/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml b/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml
> > > index e769c9bb70d8..ff5e50f65114 100644
> > > --- a/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml
> > > +++ b/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml
> > > @@ -23,6 +23,7 @@ select:
> > >            - amlogic,meson-gxbb-dwmac
> > >            - amlogic,meson-axg-dwmac
> > >            - amlogic,meson-g12a-dwmac
> > > +          - amlogic,t7-dwmac
> > >    required:
> > >      - compatible
> > >
> > > @@ -84,6 +85,49 @@ allOf:
> > >          rx-internal-delay-ps:
> > >            default: 0
> > >
> > > +  - if:
> > > +      properties:
> > > +        compatible:
> > > +          contains:
> > > +            const: amlogic,t7-dwmac
> > > +    then:
> > > +      properties:
> > > +        clocks:
> > > +          items:
> > > +            - description: GMAC main clock
> > > +            - description: First parent clock of the internal mux
> > > +            - description: Second parent clock of the internal mux
> > > +            - description:
> > > +                clock of the pipeline stage inserted in the bus path between
> > > +                the controller and the DRAM. Without it, the controller cannot
> > > +                complete DMA transfers.
> > > +            - description:
> > > +                clock of the register block holding PRG_ETH0 and PRG_ETH1.
> > > +                Without it, the block reads as zero and ignores writes.
> > > +
> > > +        clock-names:
> > > +          items:
> > > +            - const: stmmaceth
> > > +            - const: clkin0
> > > +            - const: clkin1
> > > +            - const: pipeline
> > > +            - const: pclk
> > > +
> > > +        # The PHY adds the 2ns RGMII delays, see ethernet-controller.yaml.
> > > +        # The RX delay line of this glue is fine tuning in 200ps steps,
> >
> > Sounds like constraints:
> >
> > maximum: 2000
> > multipleOf: 200
> 
> Yes, with maximum: 3000: the field is four bits, 0 to 15 steps of
> 200ps.
> >
> > > +        # added on top of what phy-mode describes. The TX side has no fine
> > > +        # tuning: its only step is a quarter of the clock period, the full
> > > +        # 2ns at 1Gbit/s, so the TX property is not accepted.
> >
> > Move this to tx-internal-delay-ps. You can (kind of ackwardly) do:
> >
> > tx-internal-delay-ps:
> >   description: ...
> >   not: {}
> 
> dt_binding_check does not accept "not" on a property under
> properties: or in an allOf entry: cell.yaml allows only description,
> deprecated, const, enum, minimum, maximum, multipleOf, default, $ref
> and oneOf there. It passes only inside if/then, and the new file has
> no if/then. So the property stays false, with the explanation as a
> comment above it.

Okay, but we should fix that.

Rob