Bridge-vlan bug? (mt7621/DSA)

[Thibaut]

> Le 6 août 2022 à 11:58, Thibaut <hacks at slashdirt.org> a écrit :
> 
>> 
>> Le 6 août 2022 à 00:50, Mark Mentovai <mark at mentovai.com> a écrit :
>> 
>> Thibaut wrote:
>>> I’m experiencing a strange bug on Yuncore AX820 (mt7621/mt7905/mt7975, DSA-enabled) when using a bridge-vlan setup. This bug affects at least OpenWRT 22.03.0-rc6.
>>> 
>>> I’m not sure whether this bug is related to this particular SoC or only to DSA as I was unable to test with another DSA-enabled device (I don’t have any). However this bug does not affect e.g. QCA non-DSA devices.
>>> 
>>> I’m running out of ideas on how to further debug this problem, so feel free to guide me if more information is needed. Please CC-me in replies.
>> 
>> This sounds very similar to the problem I experienced with the work-in-progress DSA patches for ipq40xx:
>> 
>> https://github.com/openwrt/openwrt/pull/4721#issuecomment-971162067
>> 
>> This kernel patch explains the situation fairly well:
>> 
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5f19486cee79d04c054427577ac96ed123706db
>> 
>> But the fix isn’t operative unless the switch driver opts in via assisted_learning_on_cpu_port. There were also comments from around that time that there may still be trouble with untagged traffic.
>> 
>> There’s a bit of discussion about this issue in the comments around there on the pull request. Hopefully you’ll find it helpful. It should at least get you oriented in the right direction, even if it’s not a fix for your untagged use case.
> 
> Thanks a lot for these details. Based on your input and looking at our current 5.10 source and the current upstream, it seems this might have already been fixed upstream:
> 
> https://github.com/torvalds/linux/commit/0b69c54c74bcb60e834013ccaf596caf05156a8e
> 
> I’ll check if this can be backported without too much fuss.

Backport submitted:
http://patchwork.ozlabs.org/project/openwrt/patch/20220809125947.31775-1-hacks@slashdirt.org/

It fixes the issue and applies cleanly to 22.03: I have run tests in both master and 22.03.

I will now check if I can make it work in 21.02 which is also affected.

Cheers,
Thibaut