Re: How to automatically initiate sniff mode

[Nick Pelly <npelly@google.com>]

On Mon, Feb 16, 2009 at 6:37 PM, Marcel Holtmann <marcel@holtmann.org> wrote:
> Hi Nick,
>
>> We have come across a headset (HTC M200) that does not send out a
>> sniff mode request when in idle. Our Bluez based stack also does not
>> send a sniff mode request, so we sit in a higher power state that
>> necessary. (20mA instead of 1mA).
>>
>> Some quick research suggests that we would need to send HCI Sniff Mode
>> Command (OCF 0x03) to initiate sniff mode, and that this is not yet
>> done in the Bluez code base. We do send the HCI Write Default Link
>> Policy Settings Command but, as I understand, this is only applied to
>> incoming sniff mode requests by the link manager and will not initiate
>> an LMP sniff request.
>>
>> We compared to two non-bluez mobile stacks and found the other phones
>> did automatically initiate an LMP sniff mode request.
>>
>> Is there a reason for Bluez not automatically sending HCI Sniff Mode
>> Command, or is it just a case of no-one getting around to hitting the
>> problem / implementing a fix? Or have I missed something simple?
>
> actually BlueZ has automatically sniff mode since a long-long time ago.
> It also would do sniff-subrate in case of Bluetooth 2.1 modules. However
> you have to enable it since by default it is off.
>
> Check /sys/class/bluetooth/hci0 for idle_timeout, sniff_max_interval and
> sniff_min_interval. Use idle_timeout and the others to control the
> interval values.
>

Ah, thank you! I was looking on the userspace side.

Nick