Re: brcmfmac disconnects when iwd scans

On May 2, 2025 6:10:35 PM KeithG <[email protected]> wrote:

> On Fri, May 2, 2025 at 9:45 AM Denis Kenzior <[email protected]> wrote:
>>
>> Hi Keith,
>>
>>> I am building iwd from git with those 3 patches and every time it
>>> scans, it disconnects the AP.
>>> When I use wpa_supplicant, it does not disconnect regardless of using:
>>> iw wlan0 scan passive
>>> or
>>> iw wlan0 scan
>>>
>>> it is only with iwd that it disconnects and only with iwctl. If I run
>>> 'iw wlan0 scan passive' or
>>> 'iw wlan0 scan' when iwd is running and wpa_aupplicant is removed, It
>>> seems to be OK.
>>> My laptop shows a disconnect, sometimes, but when I check the wlan0 on
>>> the laptop
>>> it is still connected to the ap running on the RPi. I think it looses
>>> the connection for a
>>> second but reconnects. If I run the 'iwctl station wlan0 scan' it will
>>> disconnect and not reconnect.
>>> When it does, the ap0 gets to a strange state as it takes a number of
>>> attempts to get it to
>>> reconnect and sometimes it requires a tear down and restart of ap0
>>> before I can reconnect
>>>
>>> This is an iwmon log of my RPi.
>>> https://drive.google.com/file/d/1WNZz0dOip0XZZVIOs7RGcYIeLY2W4bXC/view?usp=sharing
>>> I had connected to it from my laptop. I then ran:
>>>
>>> # iw wlan0 scan
>>> # iw wlan0 scan passive
>>> # iwctl station wlan0 scan
>>>
>>> after I ran the last command, the Pi's ap0 disconnected from my laptop.
>>
>> I do indeed see the local AP interface generating 'Del Station' events, which
>> means the local client was disconnected.  The funny part is that iwd ends up
>> scanning a subset of the frequencies triggered via 'iw', it just does it in two
>> sets.
>>
>> Here's what I see iw doing:
>>
>> < Request: Trigger Scan (0x21) len 16 [ack]                           22.190542
>> Interface Index: 3 (0x00000003)
>> Scan Flags: Mask: 0x00004000 len 4
>>     Colocated6G
>>> Event: Trigger Scan (0x21) len 364                                  22.194336
>> Wiphy: 0 (0x00000000)
>> Interface Index: 3 (0x00000003)
>> Wireless Device: 1 (0x0000000000000001)
>> Scan SSIDs: len 0
>> Scan Frequencies: len 320
>> 0: 2412 (0x0000096c)
>> 1: 2417 (0x00000971)
>> 2: 2422 (0x00000976)
>> 3: 2427 (0x0000097b)
>> 4: 2432 (0x00000980)
>> 5: 2437 (0x00000985)
>> 6: 2442 (0x0000098a)
>> 7: 2447 (0x0000098f)
>> 8: 2452 (0x00000994)
>> 9: 2457 (0x00000999)
>> 10: 2462 (0x0000099e)
>> 11: 5170 (0x00001432)
>> 12: 5180 (0x0000143c)
>> 13: 5190 (0x00001446)
>> 14: 5200 (0x00001450)
>> 15: 5210 (0x0000145a)
>> 16: 5220 (0x00001464)
>> 17: 5230 (0x0000146e)
>> 18: 5240 (0x00001478)
>> 19: 5260 (0x0000148c)
>> 20: 5280 (0x000014a0)
>> 21: 5300 (0x000014b4)
>> 22: 5320 (0x000014c8)
>> 23: 5500 (0x0000157c)
>> 24: 5520 (0x00001590)
>> 25: 5540 (0x000015a4)
>> 26: 5560 (0x000015b8)
>> 27: 5580 (0x000015cc)
>> 28: 5600 (0x000015e0)
>> 29: 5620 (0x000015f4)
>> 30: 5640 (0x00001608)
>> 31: 5660 (0x0000161c)
>> 32: 5680 (0x00001630)
>> 33: 5700 (0x00001644)
>> 34: 5720 (0x00001658)
>> 35: 5745 (0x00001671)
>> 36: 5765 (0x00001685)
>> 37: 5785 (0x00001699)
>> 38: 5805 (0x000016ad)
>> 39: 5825 (0x000016c1)
>> Scan Flags: Mask: 0x00004000 len 4
>>     Colocated6G
>>
>> While iwd does:
>> < Request: Trigger Scan (0x21) len 64 [ack]                           31.619536
>> Wireless Device: 1 (0x0000000000000001)
>> Information Elements: len 12
>> Extended Capabilities: len 10
>>     Capability: bit 19: BSS transition
>>     00 00 08 00 00 00 00 00 00 01                    ..........
>> Scan Frequencies: len 24
>> 0: 2412 (0x0000096c)
>> 1: 2437 (0x00000985)
>> 2: 2462 (0x0000099e)
>> Scan Flags: Mask: 0x00004002 len 4
>>     Flush
>>     Colocated6G
>>
>> then
>> < Request: Trigger Scan (0x21) len 248 [ack]                          32.040780
>> Wireless Device: 1 (0x0000000000000001)
>> Information Elements: len 12
>> Extended Capabilities: len 10
>>     Capability: bit 19: BSS transition
>>     00 00 08 00 00 00 00 00 00 01                    ..........
>> Scan Frequencies: len 208
>> 0: 5180 (0x0000143c)
>> 1: 5200 (0x00001450)
>> 2: 5210 (0x0000145a)
>> 3: 5220 (0x00001464)
>> 4: 5240 (0x00001478)
>> 5: 5260 (0x0000148c)
>> 6: 5280 (0x000014a0)
>> 7: 5300 (0x000014b4)
>> 8: 5320 (0x000014c8)
>> 9: 5500 (0x0000157c)
>> 10: 5520 (0x00001590)
>> 11: 5540 (0x000015a4)
>> 12: 5560 (0x000015b8)
>> 13: 5580 (0x000015cc)
>> 14: 5600 (0x000015e0)
>> 15: 5620 (0x000015f4)
>> 16: 5640 (0x00001608)
>> 17: 5660 (0x0000161c)
>> 18: 5680 (0x00001630)
>> 19: 5700 (0x00001644)
>> 20: 5720 (0x00001658)
>> 21: 5745 (0x00001671)
>> 22: 5765 (0x00001685)
>> 23: 5785 (0x00001699)
>> 24: 5805 (0x000016ad)
>> 25: 5825 (0x000016c1)
>> Scan Flags: Mask: 0x00004002 len 4
>>     Flush
>>     Colocated6G
>>
>> And about 1.5 seconds later the Del Station event comes in.
>>> Event: Del Station (0x14) len 32                                    33.560662
>> Interface Index: 7 (0x00000007)
>> MAC Address 50:84:92:A6:7A:7A
>> Generation: 0 (0x00000000)
>> Station Info: len 0
>>
>> Not really sure what could be causing this.  Maybe this is a question for 
>> Arend?
>>
>> Regards,
>> -Denis
>
> Denis,
>
> Thanks for going through this. I am still trying to get more pertinent
> information as to what may cause these disconnects. If there is
> anything I can test or more info I can provide, let me know. As it is,
> I am trying to set up hostapd/wpa_supplicant to see if it is any more
> stable.

So is this thread in any way related to the thread with subject "Cannot 
maintain an ap with brcmfmac"? I responded to that on April 21, but never 
saw any follow-up on that. It's kinda hard to debug by email especially 
when new threads are started in parallel. More than willing to help but a 
bit lost in the woods here.

Regards,
Arend