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From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: Wed, 27 Mar 2024 17:01:16 -0400
Message-ID: <CABBYNZLj8z1xbB-2Qnwiqvqw1PdLjhVy3GgZLHFirEjLE4QtAw@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 2:15=E2=80=AFPM Chris Laplante
<Chris.Laplante@ezurio.com> wrote:
>
> Hi,
>
> I have a customer with an issue where they are unable to get 30 devices p=
aired 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 SoC=
.
> 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 the=
n 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 i=
f they restart the host system (and in turn the SoC as well) they are able =
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 source =
of the problem it has something to do with the BlueZ stack configuration ( =
they are currently using the default stack configuration) and/ or the firmw=
are configuration parameters.
>
> Do you have any idea on what configuration parameters could be causing th=
is behaviour and/ or what configuration changes need to be made so that the=
y can achieve the target of pairing and bonding with 30 sensors. If you hav=
e 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 devices, 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/pair everything in parallel?

> I believe the default is set to something like 65K devices per MaxControl=
lers 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 tho=
ugh.

> I am assuming the issue isn't BlueZ specific but if there is any thoughts=
 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 RE=
CIPIENT. IT MAY NOT BE REPRODUCED OR USED WITHOUT EXPRESS WRITTEN PERMISSIO=
N OF EZURIO


--=20
Luiz Augusto von Dentz