Can't display two monitors at the same time

Question

I am a 12 hours Ubuntu 20.04 user old, came from windows 8.
my problem is that I have another monitor and want it to "extend" the display Join Displays but for a reason, both of the screens won't display together it's either the laptop screen or the external monitor. If I closed the laptop lid, then the external monitor will display, and if I opened the lid, the external monitor will show its screensaver animation and the display will be on the laptop's screen.

This is the display settings from laptop screen:

this is the display settings from laptop screen

this is what typing xrandr --query will show

Screen 0: minimum 320 x 200, current 2390 x 968, maximum 16384 x 16384
LVDS connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768      59.99*+
   1280x720      59.97  
   1152x768      59.95  
   1024x768      59.95  
   800x600       59.96  
   848x480       59.94  
   720x480       59.94  
   640x480       59.94  
VGA-0 connected 1024x768+1366+200 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768      60.00* 
   800x600       60.32    56.25  
   848x480       60.00  
   640x480       59.94  
HDMI-0 disconnected (normal left inverted right x axis y axis)

Graphics card: Radeon HD 7640G and no updates in Additional Drivers tap in Software & Updates window.

any possible solution to make both of the screens work together?

UPDATE: I installed Linux mint 20 cinnamon edition, Fedora 32 and the problem still occurs.

score 1 · Answer 1 · answered Jul 14 '20 at 19:59

1

Looking at the xrandr output, both displays are seen by your hardware. Your external monitor seems to be connected with VGA and has a resolution of 1024*768 But it also looks like the external display does not fully specify itself (edid) because it reports a physical size of 0mm x 0mm It also seems to be shifted vertically by 200pixels, the defined viewport is 2390 x 968 but this should not be a problem.

Since you already used xrandr we can try the following in a terminal

xrandr --output VGA-0 --off

This should switch off the external monitor. Now we switch it back on with it's preferred setting and putting it on the right side of your laptop screen :

xrandr --output VGA-0 --auto --right-of LVDS

Should this not work, a detailed description of your hardware might be needed, to see which driver is used for the hardware. Please share ~/.local/share/xorg/Xorg.0.log

answered Jul 14 '20 at 19:59

Ferdi

517
2
5

Thanks for helping out, the first command-line made the screen blinks, the second command line turned off the laptop screen and displayed on the external monitor. Also, I couldn't find where /.local/share/xorg/Xorg.0.log is, but there's a file has the same name in var/log folder and there's the log: https://paste.ubuntu.com/p/VYg6nwYyp3/ – Bon Echo Jul 14 '20 at 20:19
try this: xrandr --output LVDS --auto --output VGA-0 --auto --right-of LVDS – Ferdi Jul 14 '20 at 20:44
Did the same, displayed on the external screen and disabled the laptop's – Bon Echo Jul 14 '20 at 20:50
Please check the update in main question – Bon Echo Jul 15 '20 at 15:56
That is really odd, the Xrandr command should specifically enable both screens. It could really be a driver issue for this type of card. One other thing, it could also be related to the x-server. Have you tried a wayland session? – Ferdi Jul 16 '20 at 16:08
this is copied from the terminal when I execute the lspci -nn | grep -E 'VGA|Display' command 00:01.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Trinity [Radeon HD 7640G] [1002:9903] I tried to install the latest update from AMD support but out of luck because fglrx was deprecated since ubuntu 16.04 . I am writing this comment in a Wayland session and I plugged the screen in, yet xrandr doesn't detect the external monitor. I can't find what causes the problem and its exhausting because I started to love ubuntu – Bon Echo Jul 16 '20 at 22:28
Wayland does not use x-server so xrandr does not work in a wayland session. It does use the same graphics drivers. – Ferdi Jul 17 '20 at 07:33
Last time AMD issued new drivers for your APU was for Ubuntu 14.04. Apparently the kernel's Radeon driver has only limited support for this APU or It could really be a bug or a regression in the radeon driver. Perhaps you can file a bug against the Linux kernel for it? Also possible is that it is the (buggy) EDID of the monitor that is the problem. You could try to solve this using information from this question: https://askubuntu.com/questions/973499/wayland-how-to-set-a-custom-resolution – Ferdi Jul 17 '20 at 07:56

score 0 · Answer 2 · answered Jul 14 '20 at 18:32

0

It might sound obvious, but did you checked in the bios settings of your laptop if there is not a setting that managed how your graphic adaptor behaves? I have a Thinkpad where I have to define whether the Intel or Nvidia graphic adaptor should be used... Windows might handle it automatically, Ubuntu not..

answered Jul 14 '20 at 18:32

FlyingMG

1
2

thanks for your response. there's not such an option in my BIOS settings. – Bon Echo Jul 14 '20 at 19:00
What is your laptop exactly? Have you get it work the way you want (Joint displays) with Windows? – FlyingMG Jul 15 '20 at 05:17
It's Toshiba Satellite L855D with AMD® A8-4500m apu with radeon(tm) hd graphics × 4 8 Gigs of RAM 1 Terabyte HDD and 240 Gig crucial SSD which where I installed Ubuntu on. It was very easy to join display on Windows 8 like a piece of cake, the moment I attach the VGA cable it joins or dublicate the display instantly – Bon Echo Jul 15 '20 at 13:06
Please check the update in main question – Bon Echo Jul 15 '20 at 15:56

Can't display two monitors at the same time

2 Answers2