Re: [PATCH net-next v3 3/3] arm64: dts: renesas: r8a779g0: Add gPTP node

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The newly added `gptp` node claims the exact same memory and reset resources as the existing `tsn0` node, leading to `-EBUSY` probe failures and hardware state corruption if both are enabled.
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commit c52da814d390d81d618c033aea857f507bdb9ae0
Author: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

arm64: dts: renesas: r8a779g0: Add gPTP node

This commit adds a new gPTP module node to the r8a779g0 device tree, sharing
the hardware between the RAVB and RTSN Ethernet devices.

> diff --git a/arch/arm64/boot/dts/renesas/r8a779g0.dtsi b/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
> index 82a7278836e57..b9b860ef70351 100644
> --- a/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a779g0.dtsi
> @@ -589,6 +589,15 @@ tmu4: timer@ffc00000 {
>  			status = "disabled";
>  		};
>  
> +		gptp: ptp@e6449000 {
> +			compatible = "renesas,r8a779g0-gptp", "renesas,rcar-gen4-gptp";
> +			reg = <0 0xe6449000 0 0x500>;
> +			clocks = <&cpg CPG_MOD 2723>;
> +			power-domains = <&sysc R8A779G0_PD_ALWAYS_ON>;
> +			resets = <&cpg 2723>;
> +			status = "disabled";
> +		};
> +

[Severity: High]
Does adding this gptp node cause resource conflicts with the existing tsn0
node?

The new gptp node claims the 0xe6449000 memory region and the 2723 reset line.
However, looking at the existing tsn0 node right below it, tsn0 also claims
the exact same memory region and reset line.

If both nodes are enabled in a board device tree, this will lead to probe
failures when the drivers request exclusive access to the 0xe6449000 MMIO
region. Whichever driver probes second will receive an -EBUSY error.

Additionally, the rtsn driver explicitly asserts the 2723 reset line during
interface bring-up via rtsn_reset(), which would silently wipe the hardware
registers configured by the gptp driver.

Should the tsn0 node be updated to drop its gptp memory region and reset line
to safely extract the shared module?

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260701090607.1108208-1-niklas.soderlund+renesas@ragnatech.se?part=3