Re: [PATCH net-next v1 3/5] arm64: dts: s32n79: add NETC IEP18 ECAM node for ENETC PPM ports

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] dt-bindings: PCI node netc_iep18 uses msi-parent instead of msi-map breaking MSI routing
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commit 31419622a4729bd8008cf190e3a0993387a80408
Author: Claudiu Manoil <claudiu.manoil@nxp.com>

arm64: dts: s32n79: add NETC IEP18 ECAM node for ENETC PPM ports

Add the netc_iep18 PCIe ECAM host node describing the NETC integrated
endpoint bus allocated to the first Linux cohort on S32N79.

> diff --git a/arch/arm64/boot/dts/freescale/s32n79.dtsi b/arch/arm64/boot/dts/freescale/s32n79.dtsi
> index 94ab58783fdc8..671b807f1c540 100644
> --- a/arch/arm64/boot/dts/freescale/s32n79.dtsi
> +++ b/arch/arm64/boot/dts/freescale/s32n79.dtsi
> @@ -122,6 +122,30 @@ irqsteer_coss: interrupt-controller@4ed00000 {
[ ... ]
> +		netc_iep18: pcie@241200000 {
> +			compatible = "pci-host-ecam-generic";
> +			reg = <0x2 0x41200000 0x0 0x100000>;
> +			#address-cells = <3>;
> +			#size-cells = <2>;
> +			device_type = "pci";
> +			bus-range = <0x0 0x0>;
> +			msi-parent = <&its 0x0>;

[Severity: High]
Does this break MSI routing for the PCIe devices on this bus?

The GICv3 ITS requires an MSI specifier (#msi-cells = <1>), and Linux's
of_check_msi_parent() explicitly rejects msi-parent on bus nodes if the
target MSI controller has #msi-cells > 0. This causes of_msi_xlate() to
fail to locate an MSI controller, leaving the PCIe devices entirely without
an MSI domain.

Furthermore, PCI buses typically use the msi-map property to map Requester
IDs (RIDs) to MSI sideband Device IDs. Using msi-parent with an argument
maps all 256 RIDs to the exact same ITS sideband ID (0x0). This breaks MSI
isolation and contradicts the iommu-map property which maps them to distinct
Stream IDs (0xc0000 to 0xc00FF).

Should this use msi-map instead, for example:
msi-map = <0x0 &its 0xc0000 0x100>?

> +			iommu-map = <0x0 &smmu 0xc0000 0x100>;
> +			dma-coherent;
> +			status = "disabled";
> +
> +			/* All NETC PCIe functions */
> +			ranges = <0x82000000 0x0 0x48800000 0x0 0x48800000 0x0 0x4b0000>;
> +		};
> +	};

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Sashiko AI review · https://sashiko.dev/#/patchset/cover.1791548316.git.claudiu.manoil@nxp.com?part=3