I've got 22 Mainboard + CPU board combination (latest 4GB RAM versions) lying
around at home and would like to ensure that the hardware is working fine - so I
can place the order for the mass production.

However, I'm running into issues which I can't solve myself (as I am no
developer and can't even do small changes to a kernel, etc.)
I'm good with Linux, but not with developing - so I need some serious help here.

The unit I'm testing right now is one of latest batch.

Our own PyraOS usually freezes the system right after 30 seconds to 1 minute, so
not really usable.

The latest "stable" Letux (kernel 4.18.8) with LXDE as base OS (installed using
the makesd-tool) does boot fine. On two tries, it freezed after around 10 - 12
minutes sitting around idle. And about 2 - 3 minutes running the high-load
script (which ups the CPU to 1,5GHz with some loop).

I will do more testings to see if it's always around the same time.

I've made a small script that logs power supply, uptime and temperature to see
if it has something to do with that.

The result (incl. bootlog) is attached.
I went to bed while it was running, but you can see in the log that it freezes
after 12 minutes. Temperature is fine, voltage also seems to be fine and when
using the high-load script, the temperature is higher after a few seconds and it
still takes minutes to freeze - so we can assume that the freeze doesn't have
anything to do with temperature CPU load.

Interestingly, when I came back, the frozen unit was still on (and showed the
frozen desktop screen), but pretty warm - a lot warmer compared to it just
idling.

I've added the new temperature and charging state at the end of freeze.txt as
well.

Some things we know:

* Both askarus' and aTc's older Pyras (older Mainboard, 2GB RAM CPU board
without our optimizations) are stable with kernel 4.15. aTc mentioned he'd been
running it off USB for days whereas askarus' Pyra runs 10 hours off battery
without freezing and in normal usage (internet, LibreOffice, etc.)
Unfortunately, the released kernel 4.15 doesn't support the new mainboards / CPU
boards for some reason, so I can't compare them.

* According to hns, even the uEVM freezes randomly with the latest kernel 4.18

* These freezes don't seem to be connected with temperature or CPU load (both
Askarus and aTcs Pyras don't have any heat sink applied, whereas the 4GB RAM
unit I've tested it on does).

* Sometimes the freeze shows random graphic glitches on the display, sometimes
the display simply freezes (memory errors?)

* The freeze might NOT be a full freeze! When using hns' QuantumStep OS (which
uses the LEDs as heartbeat), the unit also seemed to have frozen after a couple
of minutes, as the LEDs stopped blinking. However, the LCD was still updating
the graphics - VERY very slowly (1 character per 30 seconds on the terminal),
but it was still working - even though it seemed frozen at first.
This doesn't seem to be the case on LXDE, but maybe it's even slower because
there's so much going on.

* On the unit I tested, sometimes u-Boot reported that it expected 4000000 of
memory size but only found 4. This might be related to the unit - or maybe some
timings are still wrong for the 4GB RAM so there's some issue here?

* Running the uevm with little less than 5V increases the instability. As aTc
and askarus Pyra work fine with less than 5V, this shouldn't be a problem - but
I thought I'd mention it here anyways.

So I'd like to find out the reason for these random freezes are.
I've got various PCBs and cases, I can run tests - but as I can't code, I can't
play around with kernel parameters or similar, so I'm pretty limited finding out
what it could be.

That's where I need your help!
Does anyone have any ideas what the issue could be and can provide different
kernels, board files, etc. for me so I can test if that changes the behaviour?

It would also be good if someone could provide a minimal image with all non-
needed drivers disabled per default incl. instructions how I can load them
afterwards one by one (for example, let me know the modules to load and what
they're used for).

So basically, starting with minimal features to see when it fails.
Maybe further debug notices can be added so we see something on serial out just
before the crash...?

As far as I know, Tony and notaz did a memory test run for hours, so for some
reason, it didn't freeze on their boards.

Who would be willing to help me providing me files and guiding me through the
tests?

Here are some ideas that could be the reason for the freezes:

* SD-Card issues - we're running the Linux off SD Card. Not sure it likes it
when for example power breaks down or the driver does something wrong with the
SD Card (though that should probably lead to a kernel panic).

* Issues switching between various voltages / frequencies (are all the voltages
we're using in the dtb approved by TI?)

* RAM timing issues

* PALMAS power supply / timing issues. If PALMAS does something wrong, the
system could easily freeze

The biggest issue is, that for the new PCBs both hardware and software have
changed, so it's hard to compare it and rule out hardware / software issues.

Kernel 4.15 and old 2GB RAM hardware or uEVM works fine.
Kernel 4.18 doesn't work stable on old OR new hardware and neither on uEVM.

It could be hardware, software - or a mixture of both.
Well, software seems to be ONE reason at least, as 4.18 doesn't work on uEVM as
well.
But it means I can't properly test the new hardware right now - which is
critical :)

What are your ideas, how can we approach this?

Thanks a lot in advance!