Comment 0 for bug 1731467

It has been observed that sometimes it is not possible to pair with
BLE remote devices when the host system is using combo (WiFi + BT)
chip.

The root cause of the disconnection has been identified as coming from
the internal to bluez timeout. If bluez does not hear any reply from for
two seconds the link is automagically disconnected. The reason fro the
silence is not however a failure of the remote device but quite often a
delay in the WiFi/BT combo driver that causes the packages not to reach
the bluez stack.

The bug has been discussed and fixed here:

https://marc.info/?l=linux-bluetooth&m=150824844606937&w=2

[Patch]

https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=1f01d8be0e6a04bd682a55f6d50c14c1679e7571

[Impact]

Fixing this bug will enable xenial based Ubuntu core devices such as
gateways connect to various BLE sensors.

[Regression Potential]

Although the timeout has been increased the value is still very low
(4 seconds) therefore should not have a negative impact. It is
taken into consideration only during pairing and for connections that
are triggered by the scan report.

[Other Info]

The patch has been accepted by the upstream and will be a part of the next
kernel release. Currently in the bluetooth-next tree.