ath12k: WCN7850 beacon loss on narrower BSS after prior 160 MHz 6GHz association

[Jacob Wilson]

Quick correction to my original report: I initially characterized
this as a channel width issue (160 MHz > narrower), but further
testing shows it also reproduces with the Edgecore AP configured
at 80 MHz in 6GHz. The common factor across reproducing cases is a prior
association to the Edgecore EAP105, not the channel width per se.

Specifically:
  - Edgecore EAP105 at 160 MHz 6GHz > any narrower AP: reproduces
  - Edgecore EAP105 at 80 MHz 6GHz  > any other AP: reproduces
  - Between the Ruckus and Extreme APs without prior Edgecore
    association: does not reproduce

This looks more like an interaction between the Edgecore AP and
the ath12k/WCN7850 stack specifically, rather than a general
channel-width handling issue. I don't yet know what's different
about the Edgecore that triggers it. I can grab PCAPs of the association
if needed.

Given that this may be specific to one AP vendor rather than a general
issue, this may be more of an edge case. I can report back if I'm able
to recreate this in the field with other vendors.

Apologies for the incorrect framing in the original report.

Thanks,
Jacob Wilson

On Sat, Apr 11, 2026 at 2:34 PM Jacob Wilson <jacobtwilson7 at gmail.com> wrote:
>
> Hi,
>
> I have found what appears to be a repeatable issue with the QCNCM865
> M.2 (WCN7850 hw2.0) Wi-Fi radio on the 6.19 kernel. I searched through
> https://lore.kernel.org/ath12k/ and didn't find a report matching what
> I found here, but apologies if I missed something.
>
> After having a prior association to a 160MHz 6GHz BSS, when
> disconnecting and associating to a BSS with a narrower channel width
> (80, 40, or 20MHz), repeated CTRL-EVENT-BEACON-LOSS messages are seen
> in wpa_supplicant logs, and the connection to the BSS with the
> narrower channel width becomes unstable.
>
> This "beacon loss" state persists until either a system reboot or a
> manual reload of the PCIe device via:
>   echo 1 | sudo tee /sys/bus/pci/devices/0000:01:00.0/remove
>   echo 1 | sudo tee /sys/bus/pci/rescan
>
> My setup is as follows:
> OS: Gentoo Linux x86_64
> Host: HP EliteBook 845 14 inch G10 Notebook
> Kernel: 6.19.10, Gentoo dist-kernel (sys-kernel/gentoo-kernel)
> /proc/sys/kernel/tainted = 0
> Wi-Fi stack: NetworkManager and wpa_supplicant
>
> Test WAPs:
> Edgecore EAP105 (160MHz on 6GHz)
> Ruckus R310 (80MHz on 5GHz)
> Extreme AP3000 (40MHz on 6GHz)
>
> To reproduce:
> 1. I connect to the 160 Mhz 6GHz AP. The connection at that point is stable.
> 2. Disconnect manually from the 160 MHz AP and connect to any of my
> APs running a narrower channel width
> 3. Monitor wpa_supplicant logs, and I will see CTRL-EVENT-BEACON-LOSS
> within a few seconds, on a repeating cycle.
>
> Of note - when my connection is initially to a narrower channel width
> AP (80, 40, 20MHz), and I move from, say, 80MHz to 40MHz, the
> connection remains stable and beacon loss events are not seen.
>
> I'd be happy to provide full dmesg, .config, iw reg get output, or test
> patches if it's helpful
>
> Thanks,
> Jacob Wilson