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I have an Dell XPS 15 L521x Laptop with an HDMI and miniDisplay outputs only. The HDMI port works great but when I'm trying to connect to a VGA output using mini DP -> VGA adapter the OS detects the external monitor as "Laptop" or "Internal monitor" and does not actually send any output to the monitor itself.

I browsed the web and found several references to this problem with solutions that did not work for me, such as adding a mode to xrandr (Can I force VGA signal output even when xrandr shows 'disconnected'?), adding a new xorg.conf file (first answer in External monitor not detected on 13.04 on a Dell XPS 13 via Mini DP).

I'm currently running Linux Mint 15, and I tested this also with Ubuntu 14.04 on a Pendrive. Here are the system details:

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GK107M [GeForce GT 640M] (rev a1)

and

$ xrandr -q
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 32767 x 32767
LVDS1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080      60.0*+   59.9  
   1680x1050      60.0     59.9  
   1600x1024      60.2  
   1400x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9  
   1280x960       60.0  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
   1920x1080      60.0  
eDP-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 598mm x 336mm
   1920x1080      60.0*+   60.0  
   1680x1050      60.0  
   1400x1050      60.0  
   1280x1024      75.0     59.9     60.0  
   1280x960       59.9  
   1152x864       75.0     60.0  
   1024x768       75.1     60.0     59.9  
   800x600        75.0     60.3     59.9  
   640x480        75.0     60.0  
   720x400        70.1  
DVI-D-1 disconnected (normal left inverted right x axis y axis)
  1680x1050 (0x48)  146.2MHz
        h: width  1680 start 1784 end 1960 total 2240 skew    0 clock   65.3KHz
        v: height 1050 start 1053 end 1059 total 1089           clock   60.0Hz
  1280x1024 (0x4c)  108.0MHz
        h: width  1280 start 1328 end 1440 total 1688 skew    0 clock   64.0KHz
        v: height 1024 start 1025 end 1028 total 1066           clock   60.0Hz
  1024x768 (0x51)   65.0MHz
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock   48.4KHz
        v: height  768 start  771 end  777 total  806           clock   60.0Hz
  800x600 (0x54)   40.0MHz
        h: width   800 start  840 end  968 total 1056 skew    0 clock   37.9KHz
        v: height  600 start  601 end  605 total  628           clock   60.3Hz

I assume that the DP1 mode that appears in the xrandr output is there only because I added it and not because it was automatically detected. Here is a picture of how the GUI shows the two monitors and detects both as internal:

enter image description here

I am aware that this question is very similar to https://askubuntu.com/questions/244266/mini-dp-port-not-working-in-xps-15-l521x but I thought that since that issue seemed to be still open and is different from my situation (my computer detects the external monitor, but incorrectly) I will ask again.

Any help will be appreciated!

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I have the same laptop with 3 monitors attached and working. The problem comes with the nvidia drivers. All the 3 monitors (2 external + the internal one) working only when I'm using the nouveau drivers.

Upgrading from 14.04 to 16.04 doesn't effect that behaviour, 3 monotors still working with a minor cursor flickering that you can get used to it.

Howerver updating to 16.04.2 caused me some issues on the screen attached on the mini display port since it seems that the output isn't hardware accelerated. I've to figure it out.

  • Hi grgtvs, thanks for your update. Since I wrote the question I realized that the problem is that I need to run two X-Servers, one for each graphics card. Since I was not interested in doing that, I simply bought an HDMI->VGA adapter and used solely the HDMI port. I'm now on ArchLinux and still didn't bother fixing it. I just ignore the miniDisplay port. – Omri Har-Shemesh Feb 16 '17 at 12:59
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The second display works just fine in Ubuntu 14.04, on XPS 15. (Unfortunately a second external screen doesn't seem to work, Ubuntu or Windows).

I'm using the Nvidia driver, (in "Additional Drivers" app), but that may not be necessary. Just go to screens and choose to mirror or extend screen.

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