Re: stable-rc/linux-4.14.y bisection: baseline.login on meson8b-odroidc1

["Linux regression tracking (Thorsten Leemhuis)" <regressions@leemhuis.info>]

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

On 10.04.23 08:06, Ricardo Cañuelo wrote:
> Culprit:
> https://lore.kernel.org/r/20211227180026.4068352-2-martin.blumenstingl@googlemail.com
> 
> On lun 27-12-2021 19:00:24, Martin Blumenstingl wrote:
>> The dt-bindings for the UART controller only allow the following values
>> for Meson6 SoCs:
>> - "amlogic,meson6-uart", "amlogic,meson-ao-uart"
>> - "amlogic,meson6-uart"
>>
>> Use the correct fallback compatible string "amlogic,meson-ao-uart" for
>> AO UART. Drop the "amlogic,meson-uart" compatible string from the EE
>> domain UART controllers.
> 
> KernelCI detected that this patch introduced a regression in
> stable-rc/linux-4.14.y (4.14.267) on a meson8b-odroidc1.
> After this patch was applied the tests running on this platform don't
> show any serial output.
> 
> This doesn't happen in other stable branches nor in mainline, but 4.14
> hasn't still reached EOL and it'd be good to find a fix.
> 
> Here's the bisection report:
> https://groups.io/g/kernelci-results/message/40147
> 
> KernelCI info:
> https://linux.kernelci.org/test/case/id/64234f7761021a30b262f776/
> 
> Test log:
> https://storage.kernelci.org/stable-rc/linux-4.14.y/v4.14.311-43-g88e481d604e9/arm/multi_v7_defconfig/gcc-10/lab-baylibre/baseline-meson8b-odroidc1.html

Lo! From the earlier discussion[1] it seems the mainline developers of
the patch-set don't care (which is fine). And the stable team always has
a lot of work at hand, which might explain why they haven't looked into
this. Hence let me try to fill this gap a little here by asking:

Have you tried if reverting the change on top of the latest 4.14.y
kernel works and looks safe (e.g. doesn't cause a regression on its own)?

I also briefly looked into "git log v4.14..v4.19 --
arch/arm/boot/dts/meson.dtsi" and noticed commit 291f45dd6da ("ARM: dts:
meson: fixing USB support on Meson6, Meson8 and Meson8b") [v4.15-rc1]
that mentions a fix for the Odroid-C1+ board -- which afaics wasn't
backported to 4.14.y. Is that maybe why this happens on 4.14.y and not
on 4.19.y? Note though: It's just a wild guess from the peanut gallery,
as this is not my area of expertise!

Ciao, Thorsten

[1]
https://lore.kernel.org/lkml/20230405132900.ci35xji3xbb3igar@rcn-XPS-13-9305/

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
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If I did something stupid, please tell me, as explained on that page.

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