Re: [PATCH 08/10] arm64: dts: exynos5433: Re-order nodes to match coding style

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Reordering device tree `cpu` nodes by unit-address changes the logical CPU numbering, fragmenting cluster groupings and breaking userspace expectations.
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commit 42e710983fc6263e0bd5798117a1ac4661f1ffa1
Author: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

arm64: dts: exynos5433: Re-order nodes to match coding style

This patch reorders nodes in the Exynos 5433 device tree to alphabetical order
to comply with DT style checks. In doing so, it moves the Cortex-A57 cpu nodes
to appear before the Cortex-A53 cpu nodes.

> diff --git a/arch/arm64/boot/dts/exynos/exynos5433.dtsi b/arch/arm64/boot/dts/exynos/exynos5433.dtsi
> index d318c87effaa6..3e67d9091a191 100644
> --- a/arch/arm64/boot/dts/exynos/exynos5433.dtsi
> +++ b/arch/arm64/boot/dts/exynos/exynos5433.dtsi
[ ... ]
> @@ -90,136 +90,136 @@ core3 {
>  			};
>  		};
>  
> -		cpu0: cpu@100 {
> +		cpu4: cpu@0 {
>  			device_type = "cpu";
> -			compatible = "arm,cortex-a53";
> +			compatible = "arm,cortex-a57";

[Severity: High]
Does reordering these nodes by unit-address change the logical CPU numbering
and fragment the cluster groupings?

During boot, arch/arm64/kernel/smp.c:of_parse_and_init_cpus() iterates through
the CPU nodes in the exact order they appear in the device tree. The boot CPU
(A53 cpu@100) always receives logical ID 0.

Before this patch, the A53 nodes appeared first, yielding contiguous logical
IDs 0-3 for the A53 cores and 4-7 for the A57 cores.

Because this patch moves the A57 nodes (cpu@0 through cpu@3) before the
remaining A53 nodes, the kernel will assign logical IDs 1-4 to the A57 cores
and 5-7 to the remaining A53 cores.

Could this fragment the logical clusters into A53: 0, 5, 6, 7 and A57:
1, 2, 3, 4, breaking userspace expectations (like thermal daemons or taskset
configurations) that expect logical CPUs 0-3 to be the little cores and 4-7 to
be the big cores?

>  			enable-method = "psci";
[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260911-b4-dts-samsung-cleanup-strict-continued-v1-0-9aa55051c42b@oss.qualcomm.com?part=8