Re: d-bus or management api for beacon stuff

[Brennan Ashton <brn@deako.com>]

On Tue, 2016-11-29 at 16:01 -0500, Don Zickus wrote:
> On Tue, Nov 29, 2016 at 11:56:03AM -0800, Brennan Ashton wrote:
> > 
> > > 
> > > > 
> > > > SetDiscoveryFilter might also be necessary/helpful.
> > > 
> > > Yep, the SetDiscoveryFilter might be the way to go, the only
> > > missing
> > > part that it doesn't do right now is to disable duplicate
> > > filtering,
> > > but we might need some flag with a big warning that this will
> > > spam
> > > the
> > > bus like crazy or perhaps it can only be used along RSSI
> > > filtering,
> > > which is to prevent people to use advertisement/scanning APIs as
> > > a
> > > transport over D-Bus.
> > > 
> > > We could offer a file descriptor based solution for transport
> > > emulation using scanning/advertising to prevent spamming D-Bus
> > > but
> > > that has to play nicely with other application, either that or we
> > > only
> > > allow this over MGMT interface which is what we suggest in case
> > > there
> > > is no other use for Bluetooth in the system.
> > > 
> > > And btw, I wouldn't account Android and other mobile OSes
> > > allowing
> > > such raw access for much longer, it takes way too much power and
> > > can
> > > probably block any other Bluetooth peripheral to work, so it is
> > > probably only good to write packet sniffer and other debug tools
> > > on
> > > top of the system but it really offer nothing to the regular
> > > user.
> > 
> > I have had to resort to using the HCI interface to work with
> > scanning
> > and advertising beacon packets.  I had mentioned in an earlier
> > thread
> > the issue with duplicates.  Not only do you end up with a lot of
> > spam
> > on the dbus interface you end up with an ever increasing number of
> > bluetooth devices.  The Bluetooth mesh uses this transport, so I
> > really
> > would like to see a nice interface to support rx/tx of these
> > packets.
> 
> Hi,
> 
> Sorry for being ignorant (as I can't quite find the filter duplicate
> code
> other than the setting of the bit), but would throttling work
> here?  Cap the
> duplicates at say every 100ms or 10x/second.  That probably won't
> help with
> power consumption (unless start/stop of the radio is quick?).
> 
> Just trying to help move this along..  willing to code/test.
> 
> Cheers,
> Don
> 
The thread I mentioned is here:
https://marc.info/?t=147345134200002&r=1&w=2

The constant of interest is this LE_SCAN_FILTER_DUP_ENABLE.  I had to
recompile with this disabled because I never wanted the filter for my
application.  I had proposed making this an option in the adaptor
interface, but there did not seem to be any interest.

--Brennan