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Subject: Re: Should we disable ERTM as default?
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <CAPHZWUe9sLt8jsD57i3=PQxMfjODP7dUYLBm2qpSXFdgd9cvAQ@mail.gmail.com>
Date:   Wed, 3 Jun 2020 19:40:31 +0200
Cc:     Bluez mailing list <linux-bluetooth@vger.kernel.org>,
        ChromeOS BT Qualification <chromeos-bt-qual@google.com>
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To:     Yun-hao Chung <howardchung@google.com>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Yun-hao,

> When I ran the following tests in PTS qualification on Chrome OS, I
> couldn’t pass all of them because they all failed to create an AVDTP
> connection with channel type as ‘Streaming’ or ‘Enhanced
> Retransmission’.
> 
> - 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’t want to change its mode even though it
> claims it supports them. Our question is do we still want to enable
> this feature as default?

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