Re: [PATCH 0/2] {vision/navigation}-mezzanine: Fix overlay root node

[Dmitry Baryshkov]

On Wed, Feb 26, 2025 at 07:29:54PM +0500, Nikita Travkin wrote:
> While considering to propose WoA EL2 dt overlays upstream I was looking
> at existing overlays and noticed that some of them are broken: they put
> seemingly meaningful fixups into the overlay's "/" node, which places
> them into the overlay "metadata" itself, not into a fixup fragment to be
> applied to the actual dtb. This series fixes those two by changing to
> full path "&{/}" which should work as it was initially intended.
> 
> See demonstration of the problem below:
> 
> $ cat base.dts
> /dts-v1/;
> / {
> 	compatible = "fake,board";
> 	fake,value = <42>;
> };
> 
> $ cat extra.dtso
> /dts-v1/;
> /plugin/;
> 
> / {
> 	foo;
> 	bar { baz; };
> };
> &{/} { whatever-comes-next-after-baz; };
> 
> $ dtc base.dts -o base.dtb
> $ dtc extra.dtso -o extra.dtbo
> $ fdtoverlay -i base.dtb -o combine.dtb extra.dtbo
> $ dtc base.dtb
> /dts-v1/;
> 
> / {
> 	compatible = "fake,board";
> 	fake,value = <0x2a>;
> };
> 
> $ dtc extra.dtbo
> /dts-v1/;
> 
> / {
> 	foo;
> 
> 	bar {
> 		baz;
> 	};

Is this behaviour documented somewhere? I'd say, it would be a surprise
to me.

> 
> 	fragment@0 {
> 		target-path = "/";
> 
> 		__overlay__ {
> 			whatever-comes-next-after-baz;
> 		};
> 	};
> };
> 
> $ dtc combine.dtb
> /dts-v1/;
> 
> / {
> 	whatever-comes-next-after-baz;
> 	compatible = "fake,board";
> 	fake,value = <0x2a>;
> };
> 
> In the resulting dtb foo bar and baz are missing.
> 
> Signed-off-by: Nikita Travkin <nikita@xxxxxxx>
> ---
> Nikita Travkin (2):
>       arm64: dts: qcom: qrb5165-rb5-vision-mezzanine: Fix broken overlay root
>       arm64: dts: qcom: sdm845-db845c-navigation-mezzanine: Fix the overlay root
> 
>  arch/arm64/boot/dts/qcom/qrb5165-rb5-vision-mezzanine.dtso       | 2 +-
>  arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> ---
> base-commit: 8433c776e1eb1371f5cd40b5fd3a61f9c7b7f3ad
> change-id: 20250226-qcom-nonroot-overlays-bfe21d33be8c
> 
> Best regards,
> -- 
> Nikita Travkin <nikita@xxxxxxx>
> 

-- 
With best wishes
Dmitry