Re: [PATCH 1/7] arm64: dts: qcom: shikra-cqm-evk, shikra-cqs-evk: Add HDMI overlay

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] arm64: dts: qcom: unit_address_vs_reg warning on panel@0 in HDMI overlay
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commit 76425af69dfb56a6561d933cc0de85c2b87df761
Author: Mohit Dsor <mohit.dsor@oss.qualcomm.com>

arm64: dts: qcom: shikra-cqm-evk, shikra-cqs-evk: Add HDMI overlay

This commit adds a device tree overlay for the Shikra evaluation kits to
enable hdmi output via the lt9611uxd bridge on i2c4 and disable the default
dsi0 panel node.

> diff --git a/arch/arm64/boot/dts/qcom/shikra-cqm-cqs-evk-hdmi.dtso b/arch/arm64/boot/dts/qcom/shikra-cqm-cqs-evk-hdmi.dtso
> new file mode 100644
> index 0000000000000..a7b77114061a5
> --- /dev/null
> +++ b/arch/arm64/boot/dts/qcom/shikra-cqm-cqs-evk-hdmi.dtso

[ ... ]

> +&mdss_dsi0 {
> +	panel@0 {
> +		status = "disabled";
> +	};
> +};

[Severity: Low]
Does defining panel@0 inside &mdss_dsi0 without a reg property trigger a
dtc unit_address_vs_reg warning when building device trees with extra
warnings enabled?

In scripts/Makefile.dtbs, -Wno-unit_address_vs_reg is not passed to dtc
when extra warnings are enabled:

scripts/Makefile.dtbs:
ifeq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
DTC_FLAGS += -Wno-unit_address_vs_reg \
...

When dtc compiles shikra-cqm-cqs-evk-hdmi.dtso, check_unit_address_vs_reg()
in scripts/dtc/checks.c only exempts the fragment node that directly
contains __overlay__, not child nodes nested inside __overlay__:

scripts/dtc/checks.c:check_unit_address_vs_reg() {
	if (get_subnode(node, "__overlay__")) {
		/* HACK: Overlay fragments are a special case */
		return;
	}
	...
	} else {
		if (unitname[0])
			FAIL(c, dti, node, "node has a unit name, but no reg or ranges property");
	}
}

Because panel@0 has a unit address and no reg property in the overlay, dtc
warns on /fragment@2/__overlay__/panel@0.

Could panel@0 be given a label in arch/arm64/boot/dts/qcom/shikra-cqm-evk.dts
and arch/arm64/boot/dts/qcom/shikra-cqs-evk.dts so the overlay can disable it
via a top-level phandle reference (or specify #address-cells, #size-cells,
and reg = <0> here)?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261021-shikra_display_overlays-v1-0-adaea735999f@oss.qualcomm.com?part=1