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Subject: Re: wilc1000: AP mode issue
From:   David Mosberger-Tang <davidm@egauge.net>
To:     Ajay.Kathat@microchip.com
Cc:     linux-wireless@vger.kernel.org
Date:   Wed, 12 Apr 2023 16:53:58 -0600
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On Wed, 2023-04-12 at 21:10 +0000, Ajay.Kathat@microchip.com wrote:
> Hi David,
>=20
> On 4/12/23 12:47, David Mosberger-Tang wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know =
the content is safe
> >=20
> > Ajay,
> >=20
> > OK, here is a simpler test case:
> >=20
> > - Setup wlan0 to connect to an existing access point.
> >   In my case, wlan0 ends up with IP address 172.17.2.230.
> >=20
> > - Start hostapd on wlan0tst with these commands:
> >=20
> > ---
> > cat > hostapd-wlan0tst.conf <<EOF
> > interface=3Dwlan0tst
> > hw_mode=3Dg
> > channel=3D6
> > ieee80211n=3D1
> > wmm_enabled=3D1
> > ssid=3DWLAN0TST
> > wpa=3D2
> > wpa_passphrase=3DSOME_PASSWORD
> > EOF
> > iw dev wlan0 interface add wlan0tst type __ap
> > ip link set dev wlan0tst address 12:34:56:78:9a:bc
> > ip addr add 10.234.193.42/24 dev wlan0tst
> > hostapd hostapd-wlan0tst.conf
> > ---
> >=20
> > - Connect another computer to WLAN0TST
> >=20
> > When I try the above, usually WLAN0TST works fine but as soon as it sta=
rts up,
> > pings to 172.17.2.230 stop.  Sometimes, WLAN0TST starts up fine, but af=
ter a few
> > seconds, the client's connection gets shut down and WLAN0TST stops
> > working (or even being advertised).  When that happens, pings to 172.17=
.2.230
> > start working again.
> >=20
> > I don't think the issue is really AP-mode specific though.  I also see =
issues
> > when trying to create a virtual interface that connects to another acce=
ss point:
>=20
> In wilc1000, the concurrent mode is only supported on a single channel.

Ahh, now that makes sense.  I take it that's a physical limitation?

> I suspect the STA and AP are started on different channels. Because of
> that, the existing interface is getting affected when other interface is
> started.

Yep.  I wasn't really paying too much attention to the channels as I
was assuming they could be separate for distinct virtual interfaces
and, at first blush, it did look like it was working fine.

> Once the station is connected to AP on wlan0 interface, try using the
> same channel number to run hostapd on wlan0tst interface.

Confirmed.  I just tried that and was able to successfully connect with
Android 13, Android 9, and iOS devices without problem!

I guess I'll have to use hostapd_cli chan_switch to ensure the AP
channel stays in sync with the station's channel and hope that any
clients connected to the AP will update seamlessly if and when the
channel switches.

Would it be difficult to output an error when two virtual interfaces
are configured for different channel numbers?

In any case, thanks for your help - much appreciated!

  --david

>=20