Cannot activate third display

Bug #1561452 reported by Aki Tuomi on 2016-03-24
This bug affects 1 person
Affects Status Importance Assigned to Milestone
xserver-xorg-video-intel (Ubuntu)

Bug Description

When trying to extend desktop to third display, following error is given. It can be configured as mirror of DP-1-2 but not as extended display.

# xrandr --verbose --output eDP1 --primary --output DP-1-2 --right-of eDP1 --output DP-1-4 --right-of DP-1-2 --mode 1920x1080
screen 0: 5760x1080 1525x286 mm 95.92dpi
crtc 0: 1920x1080 60.05 +0+0 "eDP1"
crtc 4: 1920x1080 60.00 +1920+0 "DP-1-2"
crtc 5: 1920x1080 60.00 +3840+0 "DP-1-4"
xrandr: Configure crtc 5 failed
crtc 0: disable
crtc 1: disable
crtc 2: disable
crtc 3: disable
crtc 4: disable
crtc 5: disable
crtc 6: disable
crtc 7: disable
screen 0: revert
crtc 0: revert
crtc 1: revert
crtc 2: revert
crtc 3: revert
crtc 4: revert
crtc 5: revert
crtc 6: revert
crtc 7: revert

Steps to reproduce:
1. Take one Dell Precision M4800 laptop
2. Attach two external displays with DP
3. Install ubuntu 16.04
4. displays are not extended to third display

Expected behaviour:
In 14.04 and 15.10 display was automatically activated and extended. This is what I hoped.

Actual behaviour:
Display stays blank and cannot be activated even with xrandr.

Aki Tuomi (cmouse-desteem) wrote :
Aki Tuomi (cmouse-desteem) wrote :

After much experimenting, the problem seems to be with the nvidia driver. Updating it to nvidia-361 made *this* problem go away, except it renamed all outputs, refused to show anything on eDP-1 and made the whole thing hung in 5 minutes after reboot. Reverted to 15.10 which has less difficulties.

Aki Tuomi (cmouse-desteem) wrote :

Clarification on last comment, it did show black screen on eDP-1, which changed to having image if one logged out. After logging in, it turned into black screen with garbled 2mm band at top of the screen. Mouse was displayed on the screen if moved there, but as I said, the entire machine tended to hung completely in about 5 minutes, so I could not do that much testing.

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