Re: [PATCH 1/1] dt-bindings: net: snps,dwmac: Document queue config subnodes

[Sebastian Reichel]

Hi,

On Mon, Oct 24, 2022 at 07:28:29PM -0400, Krzysztof Kozlowski wrote:
> Old binding did not document "tx-queues-config". Old binding had
> "snps,mtl-tx-config" which was a phandle, so this is an ABI break of
> bindings.
>
> You are changing the binding - adding new properties.

The new binding still has the phandle. The only thing I changed is
explicitly allowing the referenced node to be a subnode of the dwmac
node. This is 100% compatible, since the binding does not specify
where the referenced node should be. Only the example suggested it
could be next to the ethernet node. But changing any properties in
the config node means a ABI break requiring code changes.

Note, that right now 4/7 devicetrees with snps,mtl-tx-config already
follow the scheme I documented. The other 3 have the queue config
below the root node like the current example:

has the queues config in /:
 * arch/arm/boot/dts/artpec6.dtsi
 * arch/arm64/boot/dts/mediatek/mt2712e.dtsi
 * arch/arm64/boot/dts/qcom/sa8155p-adp.dts

has the queues config in the ethernet node:
 * arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi
 * arch/arm64/boot/dts/freescale/imx8mp-evk.dts
 * arch/arm64/boot/dts/rockchip/rk3568.dtsi
 * arch/arm64/boot/dts/rockchip/rk356x.dtsi

After my change both are considered valid. Anyways I'm doing this
for rk3588 and planned to follow the subnode style. But if I have
to fully fix this mess I will just put the queue config to the
root node instead and let somebody else figure this out.

-- Sebastian

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