Re: [PATCH 1/3] dt-bindings: dsa: microchip: add KSZ low-loss cable errata properties

[Rob Herring (Arm)]

On Thu, 26 Mar 2026 10:10:21 +0100, Fidelio Lawson wrote:
> Microchip KSZ87xx switches are affected by the "Module 3: Equalizer fix
> for short cables" erratum described in DS80000687C.
> The embedded PHY receivers are tuned for long, high-loss cables,
> which may cause signal distortion when operated with short or low-loss
> cabling such as CAT5e or CAT6. In these cases,
> the PHY may fail to establish a link due to internal over-amplification.
> 
> Two workarounds are provided by Microchip, each configuring a different
> indirect register value to adjust the PHY equalizer settings.
> 
> This patch introduces two new device tree properties to enable and
> select the appropriate workaround:
> 
>   - microchip,low-loss-errata-enable: boolean enabling the feature
>   - microchip,low-loss-errata: selects workaround 1 or 2 (default: 1)
> 
> These properties allow board designers to opt into the errata fix
> according to the targeted cable characteristics of their platform.
> 
> Signed-off-by: Fidelio Lawson <fidelio.lawson@xxxxxxxxxx>
> ---
>  .../devicetree/bindings/net/dsa/microchip,ksz.yaml     | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:
./Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml:90:111: [warning] line too long (121 > 110 characters) (line-length)
./Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml:91:111: [warning] line too long (128 > 110 characters) (line-length)
./Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml:93:111: [warning] line too long (118 > 110 characters) (line-length)

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml: microchip,low-loss-errata: missing type definition

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260326-ksz87xx_errata_low_loss_connections-v1-1-79a698f43626@xxxxxxxxxx

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.