Created attachment 125292 [details]
full dmesg when experiencing the bug, and with drm.debug=14 log_buf_len=16M

Hello,

Since i upgraded my kernel from 4.5.4 to 4.6.3, the screen goes "blank" when
entering KMS, instead of giving the high resolution tty.
By "blank", i mean it has a uniform colour : during some boots it's pure red,
other boots it's pure magenta, and sometimes pure white.
The system is functional and i am able to ssh remotely into the machine.

My setup :
- single 2560x1440 monitor
- NVIDIA Corporation GM204 [GeForce GTX 970] (rev a1) (prog-if 00 [VGA
controller])
- both DVI and DisplayPort ports exhibit the issue
- Arch Linux

If i disable modesetting, i am able to see an image on the screen (low
resolution tty) and login to the system (no Xorg though, as expected).

I found bug 94990 which seems similar, although the symptoms are a bit
different (his monitor goes to sleep, mine remains ON and monochromatic). Also,
i have a similar motherboard (Z97-A).

So i tried one advice i saw there : booting with nouveau.config=NvForcePost=1
got me no signal instead of a uniform colour.

Sorry if i'm actually posting a duplicate, i'm not very experienced with this
:) I'll try provide more info if i can.