Received-SPF: pass (google.com: domain of linux-bluetooth-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <CAPHZWUe9sLt8jsD57i3=PQxMfjODP7dUYLBm2qpSXFdgd9cvAQ@mail.gmail.com>
 <64A824C9-7C3C-4B08-8A9E-827121C4786D@holtmann.org> <CABBYNZJtgCNeZCYQ9tWno9qD9Vi2AaJNLH5TLxMtASHS-c+ySQ@mail.gmail.com>
In-Reply-To: <CABBYNZJtgCNeZCYQ9tWno9qD9Vi2AaJNLH5TLxMtASHS-c+ySQ@mail.gmail.com>
From:   Yun-hao Chung <howardchung@google.com>
Date:   Fri, 5 Jun 2020 19:09:25 +0800
Message-ID: <CAPHZWUd=t6icDXpz=td0teDoKHtE6FMH3OPE5R+BH53GOrXAdg@mail.gmail.com>
Subject: Re: Should we disable ERTM as default?
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     Marcel Holtmann <marcel@holtmann.org>,
        Bluez mailing list <linux-bluetooth@vger.kernel.org>,
        ChromeOS BT Qualification <chromeos-bt-qual@google.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Thanks for the responses!

I think it is more likely to be the PTS's limitations. I realized the
problem is in the media channel not in the signaling channel. PTS
wants to use streaming mode, but bluez rejects it, and then PTS aborts
the test. According to the MPS 1.0 Spec 6.2, L2CAP streaming mode is
the recommendation for optimization when using MPS media control
channels, so I think bluez doesn't do anything wrong during this test.

Thanks.

On Thu, Jun 4, 2020 at 3:52 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Yun-hao,
>
> On Wed, Jun 3, 2020 at 10:43 AM Marcel Holtmann <marcel@holtmann.org> wro=
te:
> >
> > Hi Yun-hao,
> >
> > > When I ran the following tests in PTS qualification on Chrome OS, I
> > > couldn=E2=80=99t pass all of them because they all failed to create a=
n AVDTP
> > > connection with channel type as =E2=80=98Streaming=E2=80=99 or =E2=80=
=98Enhanced
> > > Retransmission=E2=80=99.
> > >
> > > - MPS/AG-SRC-TG/HFAV/CLH/SD/BV-03-I
> > > - MPS/AG-SRC-TG/HFAV/CLH/SD/BV-04-I
> > > - MPS/AG-SRC-TG/HFAV/CLH/SD/BV-05-I
> > > - MPS/AG-SRC-TG/HFAV/CLH/SD/BV-06-I
> > >
> > > It looks like bluez doesn=E2=80=99t want to change its mode even thou=
gh it
> > > claims it supports them. Our question is do we still want to enable
> > > this feature as default?
>
> We don't use ERTM on AVDTP connections, in fact only AVRCP Browsing
> channel requires that but I guess you want low level testing of L2CAP
> parameters it more common to use l2test instead, or this does not come
> from L2CAP test spec?
>
> > I am a bit confused. So when you use the disable_ertm kernel parameters=
, these test pass? But ERTM is mandatory for AVRCP 1.3 and later.
> >
> > Are we sure that MPS test cases are correct? I mean, we never required =
ERTM for HFP since that is based on RFCOMM and ERTM is useless for RFCOMM.
> >
> > Regards
> >
> > Marcel
> >
>
>
> --
> Luiz Augusto von Dentz