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From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: Wed, 27 Mar 2024 17:10:09 -0400
Message-ID: <CABBYNZJ-D=y4DtAXdyb3Py-Qf68aSYwLvL1W2_mzh4RtFS1cFw@mail.gmail.com>
Subject: Re: Maximum Bonded Devices
To: Chris Laplante <Chris.Laplante@ezurio.com>
Cc: "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Hi Chris,

On Wed, Mar 27, 2024 at 5:04=E2=80=AFPM Chris Laplante
<Chris.Laplante@ezurio.com> wrote:
>
> Thanks Luiz
>
> They are not trying to maintain 30 simultaneous connections if that is wh=
at you question was. They will only connect with say one at a time but they=
 want to maintain up to 30 bonded devices in their database.

I have something like that in my device database, in fact in a crowded
environment you may see hundreds, perhaps they are marked with
auto-connect flag and then at some point you can't really pair more
because they are always connecting/disconnecting?

> Thanks
> Chris
>
> -----Original Message-----
> From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
> Sent: Wednesday, March 27, 2024 5:01 PM
> To: Chris Laplante <Chris.Laplante@ezurio.com>
> Cc: linux-bluetooth@vger.kernel.org
> Subject: Re: Maximum Bonded Devices
>
> EXTERNAL EMAIL: Be careful with attachments and links.
>
> Hi Chris,
>
> On Wed, Mar 27, 2024 at 2:15=E2=80=AFPM Chris Laplante <Chris.Laplante@ez=
urio.com> wrote:
> >
> > Hi,
> >
> > I have a customer with an issue where they are unable to get 30 devices=
 paired and bonded when the BL5340PA (nRF5340) SoC as their central device.
> >
> > Following details might help you out-
> > 1.      They are using the hci_usb sample code as the firmware on the S=
oC.
> > 2.      The stack on the host Linux system being used is BlueZ (version=
 5.66)
> >
> > They are able to pair and bond with upto 8 devices pretty quickly and t=
hen this process slows down and they aren't able to pair with more than 12-=
15 sensors in a single go.
> > After the pairing and bonding process stagnates at around 12-15 sensors=
 if they restart the host system (and in turn the SoC as well) they are abl=
e to pair with a few more sensors but not 30 sensors.
> > So far out of the things that they have tried out to identify the sourc=
e of the problem it has something to do with the BlueZ stack configuration =
( they are currently using the default stack configuration) and/ or the fir=
mware configuration parameters.
> >
> > Do you have any idea on what configuration parameters could be causing =
this behaviour and/ or what configuration changes need to be made so that t=
hey can achieve the target of pairing and bonding with 30 sensors. If you h=
ave any more questions please let me know.
>
> Don't think there is such thing about number of paired devices limit, we =
just use lists so they be extended dynamically as you pair with more device=
s, there might be a limit on how many the controller can maintain connected=
 simultaneously though, so perhaps you want to explain a little better how =
the process of pairing goes, is that serialized or you attempt to connect/p=
air everything in parallel?
>
> > I believe the default is set to something like 65K devices per
> > MaxControllers in main.c as well as main.conf
> >
> > parse_config_u16(config, "General", "MaxControllers",
> >                                                 &btd_opts.max_adapters,
> >                                                 0, UINT16_MAX);
> >
> > # Maximum number of controllers allowed to be exposed to the system.
> > # Default=3D0 (unlimited)
> > #MaxControllers=3D0
>
> These are the number of controllers, not to confuse with paired devices t=
hough.
>
> > I am assuming the issue isn't BlueZ specific but if there is any though=
ts or guidance you may have it would be appreciated.
> >
> > Thanks
> > Chris
> >
> > THE INFORMATION CONTAINED IN THIS DOCUMENT IS OF A PROPRIETARY NATURE
> > AND IS INTENDED TO BE KEPT CONFIDENTIAL BETWEEN THE SENDER AND THE
> > INTENDED RECIPIENT. IT MAY NOT BE REPRODUCED OR USED WITHOUT EXPRESS
> > WRITTEN PERMISSION OF EZURIO
>
>
>
> --
> Luiz Augusto von Dentz
> THE INFORMATION CONTAINED IN THIS DOCUMENT IS OF A PROPRIETARY NATURE AND=
 IS INTENDED TO BE KEPT CONFIDENTIAL BETWEEN THE SENDER AND THE INTENDED RE=
CIPIENT. IT MAY NOT BE REPRODUCED OR USED WITHOUT EXPRESS WRITTEN PERMISSIO=
N OF EZURIO


--=20
Luiz Augusto von Dentz