Hi Andrey, On Wed, Aug 3, 2016 at 3:32 PM, Andrey Zheregelya <andrey.zheregelya@xxxxxxxxxxxxxxx> wrote: > Hi Luiz, > > On 03.08.2016 12:48, Luiz Augusto von Dentz wrote: >> >> Hi Andrey, >> >> On Tue, Aug 2, 2016 at 7:55 PM, Andrey Zheregelya >> <andrey.zheregelya@xxxxxxxxxxxxxxx> wrote: >>> >>> >>> >>> On 02.08.2016 18:57, Bastien Nocera wrote: >>> >>>> It's doesn't, really, until you apply heuristics to it. How do you plan >>>> to use this? >>> >>> >>> >>> Initially, there is a requirement for application to detect if a list of >>> device are available for connection or not. Before connection and after. >>> >>> As far as I understood, d-bus interface doesn't provide any way to detect >>> if >>> device is advertising or not. >>> >>> le_seen and bredr_seen provides the last time when device's advertisement >>> packet was detected (Of course if my understanding is correct) >>> >>> Application can read LastSeen time, read current time and compare with >>> application-defined timeout to make a decision if device is alive. >>> >>> Yes, this property doesn't answer to direct question "Alive or not". But >>> in >>> this way user can apply any heuristic algorithm he wants. >>> >>> And this approach doesn't require any BLE connections to device. >> >> >> But can't you use the last time you received a RSSI from the device? >> Just timestamp it in the application side, in the other hand if >> duplicate filtering is active this won't update in every packet >> received since the controller can omit them. >> > > Do you mean processing of PropertyChanged event for RSSI property? > If so, this means that GLib main loop should be used to process events. > Correct me if I'm wrong. > But application may has its own scheduler with a requirement not to use Glib > related schedule logic. It doesn't matter what binding the application will be using as soon as it got PropertiesChanged with RSSI just generate a timestamp. > > Offtopic: > Luiz, do you mean device_merge_duplicate function when mentioned about > duplicate filtering? How does it affect to RSSI updates? This is done in the controller, see the Bluetooth spec: 7.8.11 LE Set Scan Enable Command The Filter_Duplicates parameter controls whether the Link Layer should filter out duplicate advertising reports (Filtering_Enabled) to the Host, or if the Link Layer should generate advertising reports for each packet received (Filtering_Disabled). Filtering is enabled by default when doing StartDiscovery but you can disable it with SetDiscoveryFilter, but be aware that this is very spammy. -- Luiz Augusto von Dentz -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
