Reset on Beaglebone Black has become unreliable/broken

[Konstantin Kletschke]

Dear barebox community and hackers,

we use barebox 022.04.0-dirty from 
https://github.com/menschel-d/meta-barebox.git in our yocto kirkstone project.
This worked for ages in up to hundreds of BBBs without any issue.

Since last week I have the problem, that the system is not able to
reboot (linux userspace issuing reboot command) or reset (command reset
at barebox prompt) anymore in _some_ of the BBBs we got delivered from
SEEED (we get a couple of hundreds a couple of times per year). Speaking
of some one digit percentage.

Linux userspace running, issuing reboot command:

systemd-shutdown[1]: Rebooting.
reboot: Restarting system
-> Then gets stuck

Barebox prompt, issuing reset command:

Hit m for menu or ctrl-c to stop autoboot:    3
barebox at TI AM335x BeagleBone black:/ reset
-> Then gets stuck

This also applies to triggering the barebox's watchdog to trigger reset
and also the hardware line on the BBB S2 is not working on those BBBs
too! The S2 button is connected to CPU's NRESET_INOUT ball A10.

If I test those use cases with stock u-boot delivered with the BBB the
reset/reboot works each time.

>From the symptoms I guess the barebox is not able to start in each case
when it should.
Where can I start to investigate such an error, what could cause the
hardware glitching away that something is on the edge which does not
work anymore?

I learned it is something like a soft reset which is done in software,
where can I look in the sourcetree for this special part?

Kind Regards
Konstantin 
Kletschke
-- 
INSIDE M2M GmbH
Konstantin Kletschke
Berenbosteler Straße 76 B
30823 Garbsen

Telefon: +49 (0) 5137 90950136
Mobil: +49 (0) 151 15256238
Fax: +49 (0) 5137 9095010

konstantin.kletschke at inside-m2m.de
http://www.inside-m2m.de 

Geschäftsführung: Michael Emmert, Derek Uhlig
HRB: 111204, AG Hannover