Re: BLE Delayed encryption change using

[Tom Harada <tharada@lampreynetworks.com>]

Hi Marcel,
>>>> 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.
>>
>> According to the HCI dump I am not using the saved parameters. I see the
>> updated parameters getting saved, but the outgoing connection appears to not
>> be using them.
> if you run btmon, do you see a mgmt command that indicates that the parameters are actually send to userspace. I think at the moment, we only really store the parameters for devices that are a) in our device list or b) we have paired with.
>
We do see this command in btmon, right after the connection update. The 
parameters also appear to be written to /var/lib/bluetooth/.../.../info.

Regards,
Tom Harada