Odroid-C2 solid green screen on "echo c > /proc/sysrq-trigger" on Arch 4.16/4.17rc6

[maswabey@purdue.edu (Swabey, Matthew A)]

Odroid-C2 solid green screen on echo c > /proc/sysrq-trigger on Arch Linux mainline 4.16/4.17rc6
Using lightdm on xorg fb. No mali, utgard or odroid specific framebuffers. However it seems to happen on them too.

Steps to reproduce:
1. Boot
2. Echo c > /proc/sysrq-trigger with watchdog set. Or trigger the watchdog another way, i.e. watchdogd or system.
3. Watchdog causes reboot
4. Boots with screen solid green, see photo here: https://photos.app.goo.gl/9VyiweNAIMD07VSM2
	a. No error messages visible, see attached log file bundles containing dmesg, journalctl, package list, Xorg.0.log
	b. Linux-aarch64 is 4.16
	c. Linux-aarch64-rc is 4.17rc6
5. Reboot - screen back to normal and working

Thought - something about the way to trigger this reset isn't working, or a race condition is present which is being more reliably triggered? Perhaps in the dma controller or the HDMI?

Any help to track this bug down would be very helpful, or someone else who would be interested? I can't figure out where in the stack the problem is occurring, but I guess it is the bootloader.

Thanks,

Matthew

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