Created attachment 125245 [details]
dmesg from normal fedora kernel

As a reference, I attached dmesg from the normal fedora kernel

Just to exclude the possibility of faulty hardware, I tested running windows 10 from a usb-stick.
Testing both the default "microsoft basic display adapter" and intel's "Intel (R) HD Graphics" drivers, I did not encounter any problems with the graphics. Both drivers seemed to work without any problems.

Found bug https://bugs.freedesktop.org/show_bug.cgi?id=93198 (which reported that resolutions larger than 1920x1080 wasn't working through DP).

It seems I experience the same, or a similar behavior.

In my setup, the monitor's native resolution is 2560x1440.
If, using xrandr, lowering the DP resolution to e.g. 1920x1200 or 1920x1080, the DP signals starts working.
Setting the resolution back to 2560x1440 again results in a black screen.

As far as I can tell, this is reproducible and repeatable.

Sorry Mattias for long time before getting back to you. Is this problem still valid?

(In reply to Jari Tahvanainen from comment #4)
> Sorry Mattias for long time before getting back to you. Is this problem
> still valid?

My guess is yes, but I'll try whether the latest drm-intel-nightly work any better then before.

Created attachment 130169 [details]
dmesg from drm-nightly kernel

I uploaded a new dmesg dump from a run with kernel option "drm.debug=0x1e".

Summary:
I booted computer (in this case, two monitors attached, one DP and one HDMI) with drm.debug=0x1e.
After boot, when reaching gdm login, DP-monitor goes black (similar as before).
Logging in to the computer via ssh, and, using xrandr, changing DP mode to 1920x1080, make DP-monitor start showing gdm login screen.


Kernel version used:
"""commit d2ceef096ea6215af6a46a98ad5103d4d98bcb58
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sat Mar 11 11:52:09 2017 +0100

    drm-tip: 2017y-03m-11d-10h-51m-17s UTC integration manifest
"""

Hello Mattias,
Sorry for the delay, could you please test on latest drm-tip and share the results? It seems that this includes various patches for DP that could have fixed the problem already.
Thank you.

Created attachment 133092 [details]
dmesg from drm-nightly

Added dmesg from drm-nightly kernel built from

"""commit bd19696b0fe9ea167b685fe65ee2e1195e688cfd
Author: Archit Taneja <architt@codeaurora.org>
Date:   Fri Jul 28 09:44:33 2017 +0530

    drm-tip: 2017y-07m-28d-04h-11m-30s UTC integration manifest
"""

Booted with command line parameter drm.debug=0x1e.

Kernel build process, make oldconfig (starting from latest fedora 25 kernel config), make rpm.

Most recent test was conducted in a similar fashion as before, and the results are as before.

Two screens connected (via HDMI and DP).

During inital boot, both screens are showing some output.

When reaching gdm, DP-screen goes black.

(xrandr run via ssh-session)

xrandr --output DP2 --mode 1920x1200  makes DP-screen show picture again

xrandr --output HDMI3 --off  disables HDMI-screen, does not affect DP-screen

xrandr --output DP2 --mode 2560x1440  DP-screen goes black

xrandr --output DP2 --mode 1920x1200  DP-screen show picture again


Output from xrandr command:

Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
DP1 disconnected (normal left inverted right x axis y axis)
DP2 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 710mm x 400mm
   2560x1440     59.95 +
   1920x1200     59.95* 
   1920x1080     60.00    60.00    50.00    50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.95  
   1280x1024     75.02    60.02  
   1440x900      74.98    59.89  
   1280x960      60.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08  
DP3 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 connected (normal left inverted right x axis y axis)
   1920x1200     59.95 +
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   720x400       70.08  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

(In reply to mattias.slabanja from comment #9)
> 
Hello again,
Thanks for the update and the invested time, if any other information for this bug is needed, it will be posted in the comments below.

First of all. Sorry about spam.
This is mass update for our bugs. 

Sorry if you feel this annoying but with this trying to understand if bug still valid or not.
If bug investigation still in progress, please ignore this and I apologize!

If you think this is not anymore valid, please comment to the bug that can be closed.
If you haven't tested with our latest pre-upstream tree(drm-tip), can you do that also to see if issue is valid there still and if you cannot see issue there, please comment to the bug.

Closing, please re-open if still occurs.