Re: [PATCH RFC v2 2/2] arm64: dts: qcom: nord: add CoreSight debug nodes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] arm64: dts: qcom: nord: missing arm,primecell compatible on tn@115bc000
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commit 6b616ed8e06fef392cdf185844645dfbf1ca57e8
Author: Jie Gan <jie.gan@oss.qualcomm.com>

arm64: dts: qcom: nord: add CoreSight debug nodes

This commit adds the CoreSight trace topology nodes for the Qualcomm Nord
SoC, including CTCU, STM, TPDM/TPDA sources and aggregators, funnels,
replicators, TMC ETR/ETF sinks, TNoC/ITNoC nodes, and per-subsystem CTIs.

> diff --git a/arch/arm64/boot/dts/qcom/nord.dtsi b/arch/arm64/boot/dts/qcom/nord.dtsi
> index fdbe290350ddd..b03a33d99a1b7 100644
> --- a/arch/arm64/boot/dts/qcom/nord.dtsi
> +++ b/arch/arm64/boot/dts/qcom/nord.dtsi
[ ... ]
> @@ -1654,239 +1680,3181 @@ tlmm: pinctrl@f100000 {
[ ... ]
> +		tn@115bc000 {
> +			compatible = "qcom,coresight-tnoc";
> +			reg = <0x0 0x115bc000 0x0 0x3c00>;
> +
> +			clocks = <&aoss_qmp>;
> +			clock-names = "apb_pclk";

[Severity: Medium]
Should the compatible property on tn@115bc000 also include "arm,primecell"?

In Documentation/devicetree/bindings/arm/qcom,coresight-tnoc.yaml, the
binding requires both strings:

  compatible:
    items:
      - const: qcom,coresight-tnoc
      - const: arm,primecell

During bus population in drivers/of/platform.c:of_platform_bus_create(), the
kernel checks of_device_is_compatible(bus, "arm,primecell") to decide whether
to instantiate an amba_device via of_amba_device_create().

Without "arm,primecell", tn@115bc000 is created as a platform_device instead
of an amba_device. In drivers/hwtracing/coresight/coresight-tnoc.c, the
platform_driver (itnoc_driver) only matches "qcom,coresight-itnoc", while
aggregator TNoC instances are matched exclusively by the amba_driver
(trace_noc_driver).

Will omitting "arm,primecell" cause dtbs_check to fail and prevent
tn@115bc000 from probing and registering as a CoreSight link device, breaking
all trace paths routed through tn_ag?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261028075044.431228-1-shengchao.guo@oss.qualcomm.com?part=2