[Letux-kernel] Ethernet interface on Beaglebone Black broken since 5.15.0-rc1-letux+

Jean Rene Dawin jdawin at math.uni-bielefeld.de
Sun Sep 26 13:22:02 CEST 2021

H. Nikolaus Schaller wrote on Sun 26/09/21  9:08:
> Hi Andreas,
> > Am 24.09.2021 um 17:11 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > Hi,
> > 
> > On Fri, 24 Sep 2021 00:06:02 +0200
> >> 
> >> 
> >> What would be the best way to find the commit which caused the issue?
> >> 
> > If you can see this issue on mainline (maybe with just a custom config
> > or something) and do not need features in letux-kernel, then you can
> > bisect just mainline. 
> You were right to point to the obvious...
> a) mainline with omap2plus_defconfig (+ minor patches for my build system) works.
> (BTW it has no ethernet gadget).
> b) mainline with letux_defconfig (+ minor patches for my build system) fails.
> c) git diff letux-5.14 letux-5.15-rc1 arch/arm/configs/letux_defconfig
> shows a bunch of changes but none is obviously related.
> d) git diff letux-5.14 letux-5.15-rc1 arch/arm/configs/omap2plus_defconfig
> is empty but some unspecified configs may have a different default now.
> Note that I used am335x-boneblack+letux.dtb in both cases a+b (taken from
> last build of letux tree and not am335x-boneblack.dtb from mainline).
> So enough ideas for further research and potentially a bisect between
> v5.14.0 and v5.15-rc1 (each time adding letux_defconfig) may also show
> some dependency. Or a config bisect (which is more tricky but doable).


indeed, after bisecting mainline it seems

"ARM: dts: am335x-bone: switch to new cpsw switch drv"

is the culprit. It's a change to arch/arm/boot/dts/am335x-bone-common.dtsi
When booting the same kernel with am335x-boneblack+letux.dtb from 5.14.6-letux+ the 
ethernet interface works.

Jean Rene

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