[sigrok-devel] RFCOMM connections sometimes failing (EBUSY)

[Andreas S. <an...@sa...>]

Hi all,

When writing a driver for the RDTech UM24C, I started to play around with
Sigrok's Bluetooth (RFCOMM) interface. When scanning for the device,
everything works fine. However, I ran into problems when sampling the
device.

It seems like the connect() call that connects the Bluetooth socket to the
device sometimes fails with EBUSY. This usually happens if a connection to
the device was recently closed. I don't know if this is a general Bluetooth
issue on Linux or due to a dodgy interface in the device. Unfortunately,
this behaviour is consistently triggered when sampling the device since
Sigrok first opens a connection to the device to scan the device, closes
it, and then opens a new connection to sample the device.

I have hacked around the problem by changing sr_bt_connect_rfcomm to retry
a few times if connect returns EBUSY. I'm not sure if this is a good
solution though. It seems like a better solution would be to reuse the
socket that is used to scan the device, but that probably requires some API
changes.

What's the prefered solution here? I'm happy to submit my patch to retry if
that is a good enough solution for now.

Cheers,
Andreas