Re: strange behavior with synthetic ap0

On Mon, Apr 7, 2025 at 9:03 PM Denis Kenzior <[email protected]> wrote:
>
> Hi Keith,
>
> What does:
> iw phy | grep -3 'interface combinations'
> say?
>
> Typical WiFi chips support only a single channel (e.g. #channels <= 1)
>
>  >
> > How do I ensure it is on the same frequency? I would think that I
> > would have to change the freq to whatever the freq of the SSID I am
> > connecting to. The process would then have to be: query the SSID for a
> > freq then stop and restart the AP... Wouldn't this disconnect the AP0
> > from whatever is connected to it?
>
> There should be a way to tell the AP to switch the current channel.  The AP will
> inform clients about the channel switch and they should end up at the new
> frequency without losing connectivity.
>
> >
> > A bit oif background, I am trying to write a python script to do a bit
> > of magic. We use connman as the front end and iwd as the wifi
> > controller and there is no real good way to have this headless,
> > embedded device always allow a connection, so I am trying to get a
> > python script to monitor dbus and when it looses its wlan0 connection
> > to start ap0 and allow a connection that way unless it 'sees' an SSID
> > it already recognizes. In that case, I am having is down the ap0 then
> > connect to the SSID on wlan0. That works, but it must be serial: shut
> > down ap0 before connecting to SSID on wlan0 or it complains that the
> > password is bad.
> >
> > I may be mistaken, but I think that a year or so ago (kernel 5.x or
> > 6.1) it used to actually allow both simultaneously.
>
> Different firmware?
>
> >
> > I built a kernel last night so that I nave nlmon available to query
> > what is being passed if that is needed.
> >
>
> I doubt nlmon will show anything useful.  You'd need to have information about
> how the firmware / kernel driver works and any constraints.
>
> Regards,
> -Denis

Denis,

I am guessing it was an older firmware...
this is the current firmware:
[    3.587752] brcmfmac: F1 signature read @0x18000000=0x15264345
[    3.596066] brcmfmac: brcmf_fw_alloc_request: using
brcm/brcmfmac43455-sdio for chip BCM4345/6
[    3.596833] usbcore: registered new interface driver brcmfmac
[    3.880014] brcmfmac: brcmf_c_process_txcap_blob: no txcap_blob
available (err=-2)
[    3.880438] brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM4345/6
wl0: Aug 29 2023 01:47:08 version 7.45.265 (28bca26 CY) FWID
01-b677b91b

With the current version, I get this:

root@pi4(rw):~# iw phy | grep -3 'interface combinations'
         * crit_protocol_stop
         * update_connect_params
    software interface modes (can always be added):
    valid interface combinations:
         * #{ managed } <= 2, #{ P2P-device } <= 1, #{ P2P-client,
P2P-GO } <= 1,
           total <= 3, #channels <= 2
         * #{ managed } <= 1, #{ AP } <= 1, #{ P2P-client } <= 1, #{
P2P-device } <= 1,