[REGRESSION][BISECTED][STABLE] MT7925: mDNS and IPv6 broken in kernel 6.14.3 and above

[Mingyen Hsieh (謝明諺)]

On Wed, 2025-04-30 at 01:14 +0000, fossben at pm.me wrote:
> 
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> 
> Hello all,
> 
> After upgrading to 6.14.3 on my PC with a MT7925 chip, I noticed that
> I could no longer ping *.local addresses provided by Avahi. In
> addition, I also noticed that I was not able to get a DHCP IPv6
> address from my router, no matter how many times I rebooted the
> router or reconnected with NetworkManager.
> 
> Reverting to 6.14.2 fixes both mDNS and IPv6 addresses immediately.
> Going back to 6.14.3 immediately breaks mDNS again, but the IPv6
> address will stay there for a while before disappearing later,
> possibly because the DHCP lease expired? I am not sure exactly when
> it stops working.
> 
> I've done a kernel bisect between 6.14.2 and 6.14.3 and found the
> offending commit that causes mDNS to fail:
> 
> commit 80007d3f92fd018d0a052a706400e976b36e3c87
> Author: Ming Yen Hsieh <mingyen.hsieh at mediatek.com>
> Date:   Tue Mar 4 16:08:50 2025 -0800
> 
>     wifi: mt76: mt7925: integrate *mlo_sta_cmd and *sta_cmd
> 
>     commit cb1353ef34735ec1e5d9efa1fe966f05ff1dc1e1 upstream.
> 
>     Integrate *mlo_sta_cmd and *sta_cmd for the MLO firmware.
> 
>     Fixes: 86c051f2c418 ("wifi: mt76: mt7925: enabling MLO when the
> firmware supports it")
> 
>  drivers/net/wireless/mediatek/mt76/mt7925/mcu.c | 59 ++++-----------
> --------------------------------------------
>  1 file changed, 4 insertions(+), 55 deletions(-)
> 
> I do not know if this same commit is also causing the IPv6 issues as
> testing that requires quite a bit of time to reproduce. What I do
> know with certainty as of this moment is that it definitely breaks in
> kernel 6.14.3.
> 
> I've attached my hardware info as well as dmesg logs from the last
> working kernel from the bisect and 6.14.4 which exhibits the issue.
> Please let me know if there's any other info you need.
> 
> Thanks!
> Benjamin Xiao

Hi,

Thanks for reporting this issue, we will aim into this.

Can you provide me with your testing steps?

Best Regards,
Yen.