Bluetooth Low Energy bug on advertisement update (BlueZ)

Janos

I need to update the advertisement data of my peripheral at runtime in my embedded device using BlueZ.
I suspect a bug in the Qt connectivity API, as the advertisement data can never be updated, even if I reset the controller.

See this implementation of QLowEnergyControllerPrivateBluez::startAdvertising().

The new advertisement data is only used, if the advertiser member is not set yet. However, once the advertiser is set, it is never reset - so new advertisement data can never be used.

Even on QLowEnergyControllerPrivateBluez::resetController(), the advertiser is not reset, as it should be.

Is there anything I can do to update advertising, apart from creating a complete new controller object?

Edit:

The problem only seems to be in the BlueZ implementation. Android and OSX looks fine to me. I updated the topic title accordingly.

VRonin

I'd report it to https://bugreports.qt.io tbh

Janos

Thanks @VRonin , I created https://bugreports.qt.io/browse/QTBUG-70754.

Janos

So is there perhaps any way of workaround? In my case, I can think of restarting the whole application, when I need to change advertisement data. But that cannot be it, really.

aha_1980

Hi @Janos,

If I were you, I'd try to patch qlowenergycontroller_bluez.cpp and recompile qtconnectivity to test if it is working.

If yes, you can upstream the patch and it could be included in a new Qt version (which version depends on the patch complexity and impact).

I could also think of putting all your bluetooth stuff into a plugin or a DLL and unload/reload it in case you want to change the data. But that may not work if the plugin is loaded by multiple instances... again, I think fixing it in Qt is the way to go.

Edit: @kuzulis, do you have another idea?

kuzulis

@aha_1980 said in Bluetooth Low Energy bug on advertisement update (BlueZ):

Edit: @kuzulis, do you have another idea?

I have no ideas. Seems, you need to address this question to @ablasche as this question related to BlueZ. ))

AlexBlasche

Hopefully https://codereview.qt-project.org/#/c/241999/ addresses the problem.

aha_1980

Closing this one as QTBUG-70754 is already fixed. Thanks to @AlexBlasche !

linghua

This post is deleted!