Dell XPS 15 (L521x) Mini Display Port will not work

English Hardware
1

I have a Dell XPS 15 (L521x) laptop with an optimus set up. Optimus runs fine but I cannot get the mini display port to work. HDMI oddly enough seems to work fine, but I need the DP to work with my monitor.

xrandr shows this


Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 32767 x 32767
LVDS1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080      60.0*+   40.0  
   1400x1050      60.0  
   1280x1024      60.0  
   1280x960       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)
   1280x1024      60.0  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
  1280x1024_60.00 (0x13d)  109.0MHz
        h: width  1280 start 1368 end 1496 total 1712 skew    0 clock   63.7KHz
        v: height 1024 start 1027 end 1034 total 1063           clock   59.9Hz

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)

I have tried to manually set the DP1 display using xrandr, but that did not help. Does anyone have any idea how to get this running?

Thanks

2

What output do you have for:

/sbin/lspci -nnk |grep VGA -A2

ls -la /sys/class/drm/card?

ls /sys/class/drm/*/status | xargs -I {} -i bash -c "echo -n {}: ; cat {}"
3

Thank you for the response. Here is what I was able to retrieve as per your instructions:

Output for /sbin/lspci -nnk |grep VGA -A2
(Not sure why, but the NIC was output despite the grep VGA pipe)

00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)
        Subsystem: Dell Device [1028:054f]
        Kernel driver in use: i915
--
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK107M [GeForce GT 640M] [10de:0fd2] (rev ff)
        Kernel modules: nvidiafb, nouveau, nvidia
07:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 07)

Output for ls -la /sys/class/drm/card?

lrwxrwxrwx 1 root root 0 Dec 30 16:00 /sys/class/drm/card1 -> ../../devices/pci0000:00/0000:00:02.0/drm/card1

Output for ls /sys/class/drm/*/status | xargs -I {} -i bash -c “echo -n {}: ; cat {}”

/sys/class/drm/card1-DP-1/status:disconnected
/sys/class/drm/card1-HDMI-A-1/status:disconnected
/sys/class/drm/card1-LVDS-1/status:connected
/sys/class/drm/card1-VGA-1/status:disconnected
4

because of the “-An” argument passed to grep (see “man grep”) … because there was no subsystem line for the nvidia adapter, the second trailing line happened to be that related to the NIC … change n to 3 and you’d have even more info about the NIC and so forth.

Some thoughts:

  • check the dP cable, as well as the connectors on both the graphics adatper and monitor … ideally, if you can, try another dP cable

  • read through your /var/log/Xorg.0.log to see if there are any EDID errors in relation to the monitor/dP connection

  • when you connect the dP cable to the monitor, unplug the hdmi cable from any display/AV device … (see the intel series 7 PCH chipset docs for limitations applied to video outputs with systems using LVDS)

5

The cable works fine, I did not mention before but this works in windows, and I have tried several DP adapters including an HDMI one. I do not have the HDMI plugged in, though it works perfectly with the built in HDMI port.
The only error in my Xorg log is (EE) [drm] KMS not enabled.

I am thinking that this has something to do with the Optimus configuration. My fallback is to try an HDMI to DVI adapter, but I would prefer not to have to buy one at this point.

6

okay … a “with Windows” test was something I was thinking of but failed to list/mention last time … so that result is good, as it would rather appear that its solely a software issue.

The only error in my Xorg log is (EE) [drm] KMS not enabled.
Interesting given

Kernel driver in use: i915
So, since the intel drm/kms driver apparently is working, I’m not sure of the context for that error message snipet, and as I don’t have an optimus system on hand, I don’t have a comparison and can’t place from memory what it would be for … (you could post your entire xorg log to suse paste)

I am thinking that this has something to do with the Optimus configuration.
Do you require the nvidia driver? if not, you could be adventurous and tryout the realtime PM functionality now available in the nouveau stack (see https://forums.opensuse.org/english/get-technical-help-here/laptop/492447-kernel-upgrade-optimus.html#post2611882).

7

I installed Nouveau and the secondary display is working now. The only issue is that the redraw on the second screen is very slow, and occasionally only redraws part of the screen.