Bug#988966: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1 ethernet/bridge failure

From	Diederik de Haas <didi.debian@cknow.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#988966: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1 ethernet/bridge failure
Date	2022-12-15 13:10 +0100
Message-ID	<FCVdL-aPhl-11@gated-at.bofh.it> (permalink)
References	<Chmhz-7ZJ-5@gated-at.bofh.it> <Chmhz-7ZJ-5@gated-at.bofh.it>
Organization	Connecting Knowledge

Cross-posted to 2 groups.

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On Saturday, 22 May 2021 00:46:55 CET Vagrant Cascadian wrote:
> Package: src:linux
> Version: 5.10.28-1
> File: /boot/vmlinuz-5.10.0-6-armmp-lpae
> Control: block 986767 by -1
> 
> The ethernet bridge fails to work on 5.10.x (also tried 5.10.38-1),
> but works fine on 4.19.x from buster. (This was also reported in
> https://bugs.debian.org/986767)
> 
> I noticed these messages when booting up:
> 
> [    6.254047] bcm53xx stmmac-0:1e: failed to register switch: -517
> [    6.339663] bcm53xx stmmac-0:1e: failed to register switch: -517

The best way to determine what caused the change from working to not working 
is `git bisect`: https://wiki.debian.org/DebianKernel/GitBisect

It's probably possible to speed that process up by narrowing the range to 
search. Usually the quickest way is to use snapshot.debian.org and use that to 
retrieve kernels between 4.19 and 5.10 and test with that.

I've also made some observations which could also help in narrowing things 
down.
Kernel 5.10 has CONFIG_NET_DSA_TAG_BRCM_COMMON=m while it's absent in 4.19.
That setting determines whether `tag_bcrm` gets build. Bug #986767 also seems 
to indicate that that is a relevant change. It may be that lamobo-r1 needs 
additional kernel options enabled.
It appears that the networking code made a significant change between 4.19 and 
5.10 and it _could_ be DSA related.

I know OpenWrt is in the process of switching networking to DSA.
https://openwrt.org/toh/lamobo/bananapi_r1?s[]=lamobo&s[]=r1 indicates that 
the device is supported by OpenWrt version 22.03.2. It's probably worth trying 
their image and see whether it works properly. And then note which kernel 
they're using. And possibly search and/or ask for help on their forum.
https://github.com/openwrt/openwrt/issues/7817 is still open and is titled 
"sunxi / lamobo-r1: switch not working with kernel 5.4", so their issue 
tracker may also provide more info/hints.

HTH

Thread

Bug#988966: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1 ethernet/bridge failure Vagrant Cascadian <vagrant@debian.org> - 2021-05-22 01:00 +0200
  Processed: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1  ethernet/bridge failure "Debian Bug Tracking System" <owner@bugs.debian.org> - 2021-05-22 01:00 +0200
  Bug#988966: lamobo-r1 ethernet/bridge failure: Bug still exist in Daily images (2022-12-15) Bernhard <bernhard.woerner@posteo.de> - 2022-12-15 10:20 +0100
    Bug#988966: lamobo-r1 ethernet/bridge failure: Bug still exist in Daily images (2022-12-15) Diederik de Haas <didi.debian@cknow.org> - 2022-12-15 11:40 +0100
  Processed: Re: Bug#988966: lamobo-r1 ethernet/bridge failure: Bug  still exist in Daily images (2022-12-15) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2022-12-15 11:40 +0100
  Bug#988966: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1 ethernet/bridge failure Diederik de Haas <didi.debian@cknow.org> - 2022-12-15 13:10 +0100
  Bug#988966: /boot/vmlinuz-5.10.0-6-armmp-lpae: lamobo-r1 ethernet/bridge failure "Andrey Jr. Melnikov" <temnota.am@gmail.com> - 2022-12-15 20:00 +0100

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