Dual monitor setup issue with hybrid AMD/Intel graphics

fdg2018 · 2018-11-29 15:37:59

Hey everybody,

I hope I used the correct forum for this, but I got the feeling it might me a hardware issue.

The idea I had here was to connect an external monitor to my laptop via HDMI, in order to get some sort of "extended desktop".

It's a Dell Inspiron Laptop with hybrid AMD / Intel GPUs, proprietary AMD driver and the AMD GPU active:

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
	Subsystem: Dell Device 05b8
	Kernel driver in use: i915
--
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M]
	Subsystem: Dell Device 05b8
	Kernel driver in use: fglrx_pci

xrandr gives the following output:

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1366x768      60.04*+  40.02  
   1360x768      59.80    59.96  
   1024x768      60.00  
   800x600       60.32    56.25  
   640x480       59.94  
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 connected (normal left inverted right x axis y axis)
   1920x1080     60.00 +  50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.88  
   1600x900      59.98  
   1280x1024     75.02    60.02  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1440x576i     50.00  
   1024x768      75.08    60.00  
   1440x480i     60.00    59.94  
   832x624       74.55  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DP1 disconnected (normal left inverted right x axis y axis)

So the monitor connected to the HDMI port seems to work too.

However the monitor doesn't seem to get any signal ("no cable connected!").

Any idea where to start here?

Thanks in advance

iMBeCil · 2018-11-29 17:35:03

^Basically, you haven't instructed your computer to start to actually use HDMI monitor.

Start the 'arandr' program (it is by default installed on stock BL), and make HDMI output active, select resolution, and select 'Layout|Apply'. This should activate the HDMI monitor.

Last edited by iMBeCil (2018-11-29 17:35:54)

fdg2018 · 2018-11-29 18:31:46

Thanks for your reply.

I forgot to mention: I actually played around with arandr and tested a bit (since xrandr seems to recognize the external monitor, I figured it's just a matter of defining what each one has to do), so both the HDMI and LVDS monitors are active and "ready to use" in arandr.

Still the HDMI monitor doesn't get any signal. Nothing happens over there, black screen.

To rule out obvious things: The external monitor works (tested a couple of days ago on another computer).

I can bet it has something to do with the hybrid GPU hardware and / or the graphics driver, but I don't really know what the problem could be here... as soon as it gets to graphics issues on linux systems - I am totally lost.

Last edited by fdg2018 (2018-11-29 18:37:04)

iMBeCil · 2018-11-29 20:24:36

^Hm ... from your xrandr output, I can see following:

LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm

This means your laptop screen is physically connected (kind of obvious) and configured to show desktop.

HDMI1 connected (normal left inverted right x axis y axis)

This means that the HDMI cable/output is connected to something (monitor), but graphics card is not (yet) configured to show desktop on the monitor.

Perhaps, you should run xrandr directly, from the command line:

$ xrandr --output HDMI1 --auto

or more specific:

$ xrandr --output HDMI1 --mode 1920x1080 --right-of LVDS1

(see 'man xrandr'). Perhaps it will spill some error?

vinzv · 2018-12-01 10:04:58

With hybrid NVIDIA/Intel graphics I recently learned there's a xorg.conf setting prohibiting any external display use:

Option "UseDisplayDevice" "None"

Commenting this out in xorg.conf helped - maybe it's a trace for your AMD/Intel thingy?

damo · 2018-12-01 11:39:05

^ Although the default BL doesn't use xorg.conf

vinzv · 2018-12-01 20:51:33

Yes, other distributions don't do that as well but the common solution for hybrid graphics is to switch PCI IDs in custom xorg.conf files.

fdg2018 · 2018-12-03 14:55:43

Thanks for your replies so far... unfortunately I didn't have time yet to do some more testing, will get back to you...

#1 2018-11-29 15:37:59

Dual monitor setup issue with hybrid AMD/Intel graphics

#2 2018-11-29 17:35:03

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#3 2018-11-29 18:31:46

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#4 2018-11-29 20:24:36

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#5 2018-12-01 10:04:58

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#6 2018-12-01 11:39:05

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#7 2018-12-01 20:51:33

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

#8 2018-12-03 14:55:43

Re: Dual monitor setup issue with hybrid AMD/Intel graphics

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