[Solved] xrandr does't detect second monitor

Jay_Aberlour · 2019-08-20 22:13:41

So, I did a fresh install of Arch the other day, but I can't figure out how to set up multihead. I followed the wiki (Xinerama, xrandr), I tried to work with WideGuy and when that didn't work, I've tried a few guides I found through a search engine. Nothing worked.
But then I noticed this issue: https://bbs.archlinux.org/viewtopic.php?id=238083
After some searching I noticed this is exactly my problem, but it can't be just a hardware thing. Before Arch I stayed on Fedora and there multihead worked out of the box. Besides that, Xfce monitor settings shows up every time I plug the HDMI in or out. This does not change the fact that xrandr can't find my monitor, but it must at least detect the thing.
I have no idea where to start to solve this problem (besides buying hardware). How can I let xrandr detect the monitor?

output lspci | grep VGA

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile)
01:00.0 VGA compatible controller: NVIDIA Corporation GP107M [GeForce GTX 1050 Ti Mobile] (rev a1)

output xrandr -q

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 340mm x 190mm
   1920x1080     60.00*+  59.93    40.00  
   1680x1050     59.95    59.88  
   1400x1050     59.98  
   1600x900      60.00    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1368x768      60.00    59.88    59.85  
   1280x800      59.81    59.91  
   1280x720      59.86    60.00    59.74  
   1024x768      60.00  
   1024x576      60.00    59.90    59.82  
   960x540       60.00    59.63    59.82  
   800x600       60.32    56.25  
   864x486       60.00    59.92    59.57  
   640x480       59.94  
   720x405       59.51    60.00    58.99  
   640x360       59.84    59.32    60.00  
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

EDIT: typo's

Last edited by Jay_Aberlour (2019-08-22 15:53:02)

seth · 2019-08-21 06:20:30

How did you configure https://wiki.archlinux.org/index.php/NVIDIA_Optimus ?

Jay_Aberlour · 2019-08-21 08:40:39

I use only my Intel-card.
Everything I did to install the Nvidia-drivers caused problems with the xserver. Forcing me to a poweroff by holding the powerbutton. In the end I just deleted everything with Nvidia and blacklisted nouveau.

I have to mention that in Fedora I also had a bit of trouble with multihead (but it worked out of the box 90% of the time) and the Nvidia-drivers solved it. But the drivers in the main repo caused the problems I mentioned. I followed the wiki you posted (no positive result) and some forumposts were like "when I deleted the drivers, everything worked like a charm". So I choose for the last one.

seth · 2019-08-21 09:43:32

The desired output is most likely wired to the nvidia GPU, so you will have to add that in one way or another, ie. that's the problem you'll have to address first.

Jay_Aberlour · 2019-08-21 15:40:35

Allright, I'll get on to that. But I do not understand your reasoning.
"Wired to the Nvidia" Isn't the optimus laptop thing supposed to be two seperate GPU's, would could be used together?

EDIT: typo's

Last edited by Jay_Aberlour (2019-08-21 15:41:18)

seth · 2019-08-21 15:44:58

The GPUs drive CRTCs, those line out in some jacks and there you plug your monitor.
A common setup w/ optimus devices is that the IGP drives the internal display but the HDMI output "belongs" to the dedicated GPU. In order to generate an image on that output, you have to cross the GPU, even if the image is originally rendered on the IGP.

This is addressed in the linked wiki and also in eg. https://wiki.archlinux.org/index.php/Bu … VIDIA_chip because the dynamic invocation of the GPU of course causes some obstacles in this scenario. (You cannot completely shut off the GPU here)

Edit: this is spported by your GPU being an actual VGA device and not simply a "3D" thingie - the latter don't come w/ crtcs, the former typically do.

Last edited by seth (2019-08-21 15:46:17)

Jay_Aberlour · 2019-08-22 15:53:33

Thanks Seth, fixing the Nvidia drivers worked indeed.

Arch Linux

#1 2019-08-20 22:13:41

[Solved] xrandr does't detect second monitor

#2 2019-08-21 06:20:30

Re: [Solved] xrandr does't detect second monitor

#3 2019-08-21 08:40:39

Re: [Solved] xrandr does't detect second monitor

#4 2019-08-21 09:43:32

Re: [Solved] xrandr does't detect second monitor

#5 2019-08-21 15:40:35

Re: [Solved] xrandr does't detect second monitor

#6 2019-08-21 15:44:58

Re: [Solved] xrandr does't detect second monitor

#7 2019-08-22 15:53:33

Re: [Solved] xrandr does't detect second monitor

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