Re: [PATCH net-next v2 3/3] arm64: dts: renesas: r8a779g0: Add gPTP node

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Adding the standalone `gptp` node without updating the `tsn0` node creates overlapping `reg` memory regions in the device tree, which will cause `-EBUSY` probe failures.
- [Low] The `gptp: ptp@e6449000` node is placed out of order with respect to its unit address.
--

commit b1efd0e5ff9459d7a25c1c76a2bb7ef3ccffd5d2
Author: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

arm64: dts: renesas: r8a779g0: Add gPTP node

This commit adds the gPTP module node to the r8a779g0 device tree, sharing
it between the RAVB and RTSN Ethernet devices on the SoC.

> diff --git a/arch/arm64/boot/dts/renesas/r8a779g0.dtsi b/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
> index 82a7278836e57..4f2844995c44d 100644
> --- a/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
[ ... ]
> @@ -603,6 +603,15 @@ tsn0: ethernet@e6460000 {
>  			status = "disabled";
>  		};
>  
> +		gptp: ptp@e6449000 {

[Severity: Low]
This isn't a bug, but should the gptp node be placed before the tsn0 node?

Device tree nodes within a simple-bus are conventionally sorted in ascending
order by their unit address. Placing ptp@e6449000 after ethernet@e6460000
violates this ascending unit address order.

> +			compatible = "renesas,r8a779g0-gptp", "renesas,rcar-gen4-gptp";
> +			reg = <0 0xe6449000 0 0x500>;

[Severity: High]
Will this cause a resource request conflict with the tsn0 node?

The tsn0 node currently defines the same memory region:

tsn0: ethernet@e6460000 {
    compatible = "renesas,r8a779g0-ethertsn", "renesas,rcar-gen4-ethertsn";
    reg = <0 0xe6460000 0 0x7000>,
          <0 0xe6449000 0 0x500>;
    reg-names = "tsnes", "gptp";

When both nodes are enabled, their respective drivers will attempt to request
exclusive access to the 0xe6449000 region. This will result in an -EBUSY
probe failure for whichever driver initializes second.

Does the tsn0 node need to be updated to remove this overlapping region now
that a standalone gptp node is being added?

> +			clocks = <&cpg CPG_MOD 2723>;
> +			power-domains = <&sysc R8A779G0_PD_ALWAYS_ON>;
> +			resets = <&cpg 2723>;
> +			status = "disabled";
> +		};

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260612092851.2141782-1-niklas.soderlund+renesas@ragnatech.se?part=3