Re: [PATCH] Bluetooth: Enable duplicates filter in background scan

[Andre Guedes <andre.guedes@openbossa.org>]

Hi Marcel,

On 03/11/2014 01:28 PM, Marcel Holtmann wrote:
> Hi Andre,
>
>> To avoid flooding the host with useless advertising reports during
>> background scan, we enable the duplicates filter from controller.
>>
>> However, enabling duplicates filter requires a small change in
>> background scan routine in order to fix the following scenario:
>>   1) Background scan is running.
>>   2) A device disconnects and starts advertising.
>>   3) Before host gets the disconnect event, the advertising is reported
>>      to host. Since there is no pending LE connection at that time,
>>      nothing happens.
>>   4) Host gets the disconnection event and adds a pending connection.
>>   5) No advertising is reported (since controller is filtering) and the
>>      connection is never established.
>>
>> So, to address this scenario, we should always restart background scan
>> to unsure we don't miss any advertising report (due to duplicates
>> filter).
>
> don’t we need a timer that restarts the background scan in a regular interval?

We don't need that timer since the background scan is now restarted 
every time hci_update_background_scan() is called.

Regards,

Andre