brcmfmac: Can not completely turn off AP (BCM43340/2)

[Ferry Toth <fntoth@gmail.com>]

Hi,

I have an Intel Edison board with BCM43340/2.

I am currently running 6.12.39-edison-acpi-preempt-rt which is mostly 
mainline with a Yocto 5.0.11 (scarthgap) user space.

When I turn on tethering (using connman) it seems to be working fine.

But when I turn off tethering, connman seems to be believe it is off, 
but I can still see the AP with my phone.

After this wifi is dead (can not scan, connect, tether on again, 
nothing) and connman believes wifi is not supported. The only way to get 
it working after this is reboot.

While AP is up I do see in the logs:

Jul 19 22:06:34 yuna kernel: brcmfmac: brcmf_fil_cmd_data Firmware 
error: BCME_UNSUPPORTED (-23)
Jul 19 22:06:34 yuna kernel: brcmfmac: brcmf_configure_arp_nd_offload 
failed to configure (0) ND offload err = -52

But maybe more importantly when tearing down I see:
...
Jul 19 22:07:23 yuna kernel: brcmfmac mmc2:0001:1 wlan0: left 
allmulticast mode
Jul 19 22:07:23 yuna kernel: brcmfmac mmc2:0001:1 wlan0: left 
promiscuous mode
...
Jul 19 22:07:23 yuna kernel: brcmfmac: brcmf_configure_arp_nd_offload 
successfully configured (1) ARP offload to 0x9
Jul 19 22:07:23 yuna kernel: brcmfmac: brcmf_fil_iovar_data_set ifidx=0, 
name=ndoe, len=4
...
Jul 19 22:07:23 yuna kernel: brcmfmac: brcmf_fil_cmd_data Firmware 
error: BCME_UNSUPPORTED (-23)
Jul 19 22:07:23 yuna kernel: brcmfmac: brcmf_configure_arp_nd_offload 
failed to configure (1) ND offload err = -52
...

This has regressed from some older kernels (it used to work fine) , but 
I don't know exactly when, since I hadn't been testing AP for a while.

Any ideas are welcome to debug this. Or any patches to try, I can build 
on current kernel (6.16-rc6) easily and capture logs.

Currently I am using:
echo 0x1006 > /sys/module/brcmfmac/parameters/debug
journalctl -k | grep -e brcm -e "000000" -e ieee > debug.log

Thanks
Ferry