Lime2 instability

[Pawel_W]

I made some photos of my A20-Lime2 with heat sink:
http://www.fotosik.pl/pokaz_obrazek/68cbc3aa6d2c6170.html
http://www.fotosik.pl/pokaz_obrazek/a288ee10e356f77f.html
http://www.fotosik.pl/pokaz_obrazek/bc68c956f8cfc6e9.html

Heat sink is glued to memory chips by additional thermopad to offset height difference between them and CPU.
I tested Lime2 without heat sink, locked in the case - it hanged sometimes under load (Android games).
Now is much better, but without ventilation holes the heat transfer is still not sufficient for stable 24/7 100% load and the case gets warm.

[soenke]

maybe you also try to increase the core voltage and see if that solves your problem?

That huge heasink seem a little bit overkill

[JohnS]

Sounds like you're running it too fast already.  More voltage = more heat!!

John

[soenke]

If it is running on standard clock speeds, i would not change it.

I dont think that increasing the max. voltage from 1.4 to 1.45 has a sigificant impact on the CPU temperature.

He is already using a huge heatsink so i dont think his problem is related to the core temperature but more to undervoltage on certain clock speeds.

[JohnS]

The typical "standard" speed is often too fast due to being beyond the spec.  Some chips work, some don't.

Many Android tabs say they run at 1008MHz but actually don't.

He appears to have a heat problem now, as he pretty much says.

John

[olHelp]

By the way: my lime2 is over 24h uptime, with a further increase:

            912000  1430000
            864000  1375000
            720000  1275000
            528000  1175000
            312000  1125000
            144000  1075000

running with opened case. survived prolonged runs of stress with multiple i/o on all mounted filesystems. Max frequency is 960mhz

[JohnS]

1.43V is out of spec isn't it?

Yours apparently works.  It's to be expected that some will not, as indeed others have found.

Each owner can choose what they do; it may or may not work reliably.  It may not be the problem here, but there again it may be.  I'm not seeing many other suggestions.

John

[olHelp]

Meh, i am apparently still able to crash the board, even if its not reproducible. Given the increased voltage, it may be overheating now.
The last resort would be another high quality power brick, even if 2.5A (by now) should be plenty for the board+usb stick.

[JohnS]

If the CPU volts are wrong, or the frequency too high, adding current will not help.

John

[olHelp]

Yes, i am aware of that. Over at the arch linux forums someone mentioned running into instabilities with a cubieboard at default settings powered by a 2A plug, so maybe the small plugs can be instable, or i simply tried 3 different, very low quality power adaptors.

Will report back if Kernel 4.3 is out or if i feel like buying another power supply

[olHelp]

Just to update this topic:
I updated the kernel to 4.3rc5, limited the max.freq to 864mhz, using the default .dtb/voltages and got a new sd card. Board is running without attachments or case....but it still hangs.
There are two different cron-Jobs running,each full hour starts stress -c 2 with 1000s timeout, every half hour (8:30,9:30..) stress runs with -d 2 and 1000s timeout.
Both scripts may crash the system, but its not reproducible. Next stop: another board 

[JohnS]

Your kernel may be setting any/some of the on-board supplies (dcdc2 etc) to bad values and/or setting bad RAM parameters.

It may be worth asking for help on the linux-sunxi list (or IRC).  They'll want the boot (dmesg or equivalent) logs and so on.

John

[olHelp]

Oh well, i did not mean to sound that negative. Currently downloading a20-lime2_debian_3.4.90_release_2.img. At least Arch Linux was using the mainline kernel, but it still could be something wrong in main. Will report back in a week or so

[olHelp]

Hello again,

the default debian 3.4 seems to be pretty stable. Board running without case, crashes only for insane loads with multiple stress and load > 12 or so. Maybe its 100% safe with a heatsink. Now if i only could get 4.3 to be that solid

[JohnS]

I think 4.3 is not stable.  If you haven't already, referring to linux-sunxi ML / IRC may be useful.

If you build from source you can compare the machine-dependent parts.  It's probably a speed/timing issue.

John