[FS#100] PCengines APU 2c4 instant power-off issue

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Bluse-Blue (Bluse) 

Attached to Project - LEDE Project
Summary - PCengines APU 2c4 instant power-off issue
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Hi all,

In our research wifi testbed we deployed 25 new APU 2c4 routers with two Mikrotic mPCIe WiFi cards (1x R11e-2HPnD & 1x R11e-5HnD).

//problem description//
We do face the following issue: Several routers just power off after 15min to 12h of opeartion. All LEDs (network ports and system) are off.


//setup//

  * hardware: PCengines APU 2c4, 5GHz & 2,4 GHz miniPCIe Miktorik WiFi ath9k, USB stick as boot

  * software: LEDE trunk (HEAD, r1291), 5GHZ interfcae as adhoc mesh, 2,4GHz interface as AP


//troubleshooting steps//

  * There is no log message from a serial console pointing at a shutdown or halt from the Linux kernel. All dmesg & logread output looks normal.

  * The cpu temperatur is about 57C.

  * several differen power supply unit got tested but the issue still persists

  * different USB sticks were tested as boot device but the issue still persists

  * We have troubleshooted this issue a couple of day with increased logging output from Linux kernel to wireless driver (ath9k) but there is nothing special in the log, the nodes just power off at a certain point in time.

  * Several tcpdump traces from a dedicated monitor node showed also nothing special right befor the APU turns its power off. Just usual beacons were sent out.


//temporary workaround//

  * if we euqip the APU board with just one WiFi card, or disble the second WiFi card (the 2,4GHz Mikrotik R11e-2HPnD) in /etc/config/wireless the nodes just works stable for multiple days since then.


//Help needed//

Our current guess is that this issue is a hardware/current problem and not a OS or WiFi problem. We will contact the manufacturer in order to check if the power consumption from the WiFi cards is out of spec or if the boards itself have a problem providing enough power to those mPCIe devices. Does anybody has a recommendation how to further nail down such a power issue with any resonable measurement of the power suplly ?
There is already a forum thread at PCEngines tracking this issue: [[http://pcengines.info/forums/?page=post&fid=DF5ACB70-99C4-4C61-AFA6-4C0E0DB05B2A&lastp=1&id=E090912B-697F-4BB0-BA94-6EDE617C1B1B|PCEngines Forum thread]]


Greetings from Berlin
Thomas



More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=100