Re: [PATCH BlueZ v5] doc/adapter-api.txt: StartFilteredDiscovery method.

[Johan Hedberg <johan.hedberg@gmail.com>]

Hi Jakub,

On Mon, Feb 23, 2015, Jakub Pawlowski wrote:
>>>> From an API stand point, I like Johan's suggestion better. Basically
>>>> we treat all discovery APIs as "filtered" except StartDiscovery is
>>>> just a special case of StartFilteredDiscovery that has 8 dB as the
>>>> "RSSI" argument and "auto" for transport. If an app wants to use a
>>>> lower RSSI threshold then whether or not the UI will flicker should be
>>>> the responsibility of the UI code. Basically we should treat
>>>> StartDiscovery as a legacy API and perhaps mark it as deprecated while
>>>> maintaining support for it for backwards compatibility.
>>>
>>> I think you get the meaning of RSSI parameter wrong. It's not delta,
>>> chow much rssi must change to report device again (I think chromeos
>>> change that internally to something smaller). It's for proximity - if
>>> device reported RSSI is bigger than this RSSI parameter then report
>>> it, and there's no delta - we report every RSSI change we get (around
>>> 3 times/sec).
>>
>> You're right, it's just delta so I was wrong there. Still, the 8 dBm
>> thing shouldn't dictate how the discovery API should work since it
>> only affects what delta threshold to use when updating the
>> Device1.RSSI property. So, perhaps we can add a global D-Bus property
>> for RSSI delta-threshold or perhaps make that a filter parameter of
>> StartFilteredDiscovery.
>
> If we add global property for changing RSSI delta-threshold we would
> have to define api to change and probably also negotiate RSSI when
> multiple apps require different values.
> Putting it into StartFilteredDiscovery parameter seems more
> reasonable, but do we really need that ?
> Can't we just have no RSSI delta for filtered scan, and let apps
> decide on their own in their logic ?

If something like this was exposed through D-Bus then a parameter to
StartFilteredDiscovery would be the way to go, I think. However, until
we have a clear need for it we can simply keep track of this internally.
I.e. StartDiscovery keeps imposing the delta-threshold but as soon as
there's one or more StartFilteredDiscovery active this type of filtering
is removed.

Johan