On Tue, Mar 22, 2016 at 12:02:57AM +0100, Matthias Schiffer wrote:

Hi,
we're experiencing weird nondeterministic hangs during bootconsole/console
handover on some ath79 systems on OpenWrt. I've seen this issue myself on
kernel 3.18.23~3.18.27 on a AR7241-based system, but according to other
reports ([1], [2]) kernel 4.1.x is affected as well, and other SoCs like
QCA953x likewise.

Can you try 4.4 or ideally, 4.5?  There's been a lot of console/tty
fixes/changes since the obsolete 3.18 kernel you are using...

thanks,

greg k-h