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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Thu, 7 May 2020 13:29:59 -0700
Message-ID: <CABBYNZKr3r-6cXGAS3w6SR2-fw2h9gHqvnH=H7O6MSxnandUcg@mail.gmail.com>
Subject: Re: avrcp: Cannot connect Sennheiser Momentum True Wireless 2
To:     Andrey Semashev <andrey.semashev@gmail.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Hi Andrey,

On Wed, May 6, 2020 at 10:32 AM Andrey Semashev
<andrey.semashev@gmail.com> wrote:
>
> On 2020-05-06 19:56, Andrey Semashev wrote:
> > Hello!
> >
> > I have a problem connecting Sennheiser Momentum True Wireless 2
> > headphones over Bluetooth. The headphones say "Connected" and then
> > reboot immediately after. After reboot the headphones say "Power on" and
> > try connecting again, and fail the same way, and so on.
> >
> >  From the Bluetooth packet dump it looks like the problem happens after
> > bluetoothd sends AVRCP ListPlayerApplicationSettingAttributes message to
> > the headphones. The headphones send Not Implemented response and then
> > reboot. Both in the request and the response Wireshark shows warnings
> > about encoding issues.
> >
> > I'm attaching a packet dump captured from one of the connection
> > attempts. The ListPlayerApplicationSettingAttributes message is in
> > packet 262 and the response is in packet 264.
> >
> > This is on Kubuntu 20.04. I tried bluez 5.53 from Kubuntu and revision
> > 3146b7a0785758be2d4e894d44e99d29c0db983e from git master - the behavior
> > is the same.
> >
> > I've also verified that the headphones do work on Windows 10. On that
> > system, ListPlayerApplicationSettingAttributes is not present in the
> > packet exchange. I can provide the packet dump from Windows, if needed.
> >
> > I hope this is the right place to report problems like this one. If not
> > - sorry, and please point me to the right place.
> >
> > Thank you.
>
> I'll add that I can connect the headphones if I disable AVRCP by adding
> --noplugin=avrcp to bluetoothd command line.

Weird the ListPlayerApplicationSettingAttributes should only really be
used when the remote device claims to be have target role but I doubt
the headsets would be implementing that so perhaps we are not
detecting this properly, do you have the HCI traces in btsnoop format?
You can collect that with use of btmon.

-- 
Luiz Augusto von Dentz