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Subject: Re: BLE Delayed encryption change using 
From: Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <001301cfc950$ecd06240$c67126c0$@lampreynetworks.com>
Date: Sat, 6 Sep 2014 09:52:03 -0700
Cc: linux-bluetooth@vger.kernel.org
Message-Id: <3A0E8851-3F10-40A4-A5E8-43BCC727D053@holtmann.org>
References: <001301cfc950$ecd06240$c67126c0$@lampreynetworks.com>
To: Caleb Reinhold <creinhold@lampreynetworks.com>
Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Caleb,

> I am attempting to reconnect to a BLE glucometer with gatttool after pairing
> with bluetoothctl. A quick connection update seems to cause a large delay
> (around a minute) in the transmission of the LL_ENC_REQ. 
> 
> Description:
> Attempting to connect to an agent which after connecting immediately sends
> an L2CAP update connection parameters request with minimum connection
> interval set to 20 ms, and maximum connection interval set to 40 ms.
> Increasing both values by 100 ms causes the problem to stop being generated.
> 
> The problem happens only if the dongle using the Broadcom BCM20702 chipset
> is used, using a CSR8510 A10 dongle I cannot generate this issue. I am using
> BlueZ 5.22, using Linux kernel 3.10.17. The hardware platform is a Utilite.

try using a 3.17-rc3 kernel. We added storing of the connection parameters. New connections will then use the previously requested connection parameters when establishing the connection. Which means the peripheral does not have to request connection updates on every connection.

Regards

Marcel