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From: Sid Hayn <sidhayn@gmail.com>
Date: Thu, 6 Sep 2018 15:53:19 +0000
Message-ID: <CAM0KTbAF_ztZzFk_iECyPbiWY69xrcdT_93ypnuTzocjX_fRuQ@mail.gmail.com> (sfid-20180906_175332_975079_0351D0A3)
Subject: Re: mt76x0 bug report
To: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc: sgruszka@redhat.com,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Felix Fietkau <nbd@nbd.name>,
        linux-mediatek@lists.infradead.org
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Sender: linux-wireless-owner@vger.kernel.org

On Thu, Sep 6, 2018 at 11:43 AM Lorenzo Bianconi
<lorenzo.bianconi@redhat.com> wrote:
>
> >
> > On Thu, Sep 6, 2018 at 5:32 AM Stanislaw Gruszka <sgruszka@redhat.com> wrote:
> > >
> > > On Wed, Sep 05, 2018 at 08:52:18PM +0000, Sid Hayn wrote:
> > > > On Tue, Sep 4, 2018 at 5:11 PM Lorenzo Bianconi
> > > > <lorenzo.bianconi@redhat.com> wrote:
> > > > >
> > > > > >
> > > > > > I have one mt76x2u (Alfa AWUS036ACM) and a few mt76x0.
> > > > > >
> > > > > > I've noticed two additional issues in my testing.
> > > > > >
> > > > > > First issue, is that it appears the mt76x0 devices don't work properly
> > > > > > in monitor mode.  Sometimes they seem to monitor one channel properly,
> > > > > > but nothing else.  The mt76x2u works great, channel control, lots of
> > > > > > packets, etc.
> > > > >
> > > > > Could you elaborate a little bit please? how can you reproduce the issue?
> > > > > just add an interface in monitor mode and run a scan?
> > > >
> > > > Correct, standard stuff, use iw to create a monitor mode interface,
> > > > use iw to remove managed mode interface, run some tool such as kismet
> > > > or airodump-ng or even wireshark.
> > >
> > > But what exactly are the syptomps, I don't understand what you mean by
> > > "mt76x0 devices don't work properly in monitor mode" ?
> >
> > Basically, when I put a device using mt76x0 into monitor mode (adding
> > a monitor interface with iw and removing the managed interface) it
> > will not report packets on any channel, or sometimes it will report
> > packets on one channel but not any others.  I can switch channels as
> > much, for example hopping channel 1-11, but it will only see packets
> > on channel 7 and report no other packets on any other channels.  In my
> > actual test case it was channel 44 that successfully reported packets,
> > but even that mostly doesn't work.  I suspect the reason it reported
> > packets on channel 44 in one of my tests is because the channel was
> > set to 44 while in managed mode (connected to an AP).  If I put the
> > device in monitor mode before connecting to any AP, it reports packets
> > on no channels.  As such, I'm suspecting this has something to do with
> > channel control in monitor mode.
>
> What about if you do not remove the managed interface and sniff on the
> monitor one?

Actions like that have caused great problems in the past, as the
kernel won't allow channel control of a monitor interface at all when
there is a managed interface on the same phy (afaik).

But just for fun and codepath testing here are two test scenarios:

Test 1: "iwconfig t2u mode monitor"
Sees nothing on any channel, no packets reported

Test 2(requested test): "iw phy phy11 interface add t2uhmon type monitor"
Sees nothing on any channel, no packets reported.
Despite having a monitor and managed interface on the same phy,
iwconfig is reporting that the channel is changing as requested.  So
perhaps my above "afaik" comment is partially outdated.

For both tests the interface was not used to connect to any ap prior
to or during testing.

Thanks,
Zero
>
> Regards,
> Lorenzo
>
> > >
> > > > > I guess it depends on eeprom values. Could you please enable debug
> > > > > messages a paste
> > > > > syslog output?
> > > >
> > > > I don't see a mediatek specific debug near the driver selection in
> > > > menuconfig, what debug messages do you want me to enable and how?
> > >
> > > You need to uncomment this line:
> > >
> > > # ccflags-y := -DDEBUG
> > >
> > > in drivers/net/wireless/mediatek/mt76/mt76x0/Makefile
> >
> > found it.  this box takes a few min to rebuild a kernel, so I'll get
> > back with this response later today hopefully.
> >
> > Thanks,
> > Zero
> > >
> > > Thanks
> > > Stanislaw
> > >