[FS#1071] Sysupgrade fails when kernel console is disabled

[LEDE Bugs]

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

User who did this - Koen Vandeputte (xback) 

Attached to Project - LEDE Project
Summary - Sysupgrade fails when kernel console is disabled
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 - Hardware used:
- Gateworks Ventana imx6 board (GW5200)

Synopsis:

Running sysupgrade with a valid image fails if the kernel console is disabled in u-boot (setenv console ; saveenv; reset)
As soon as sysupgrade starts, the board reboots immediately.

The detected reboot reason displayed is exactly the same in both cases.


Reset cause: WDOG
 WDOG1 Reset cause: SFTW
 WDOG2 Reset cause: POR



Basically:
- Kernel console enabled  (console = ttymxc1) --> sysupgrade runs normally and succeeds
- Kernel console disabled (console =        ) --> The board reboots within 1 second as soon as sysupgrade starts


Rationale for disabling kernel console:

- This board exposes 2 UART ports for user applications (ttymxc0,  ttymxc1)
- ttymxc1 is shared with the kernel console and needs to be disabled so it does not interfere with the peripheral communication
- Both ports are used in my case (ttymxc0: GPS received  ;  ttymxc1: Iridium modem)


More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1071