Re: brcmfmac disconnects when iwd scans

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.

Keith