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Thread: Can't get dual screen to work.

  1. #1
    Join Date
    Jun 2011
    Beans
    38

    Can't get dual screen to work.

    Hi guys.

    I've always had difficulty getting dual screen up and running on my desktop running Ubuntu.

    Today I installed a 12.04 LTS XUbuntu on my desktop with a Radeon HD 7850, and when it booted I only had one screen enabled. My setup is as follows:

    Primary: 720p monitor with DVI connection.
    Secondary: 1080p monitor with DVI to VGA converter (the monitor only has VGA output - no clue why).

    I've installed the newest driver from:

    http://support.amd.com/us/gpudownload/Pages/index.aspx

    And when I run xarndr -q I get:

    Code:
    Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 1680 x 1680DFP1 disconnected (normal left inverted right x axis y axis)
    DFP2 disconnected (normal left inverted right x axis y axis)
    DFP3 disconnected (normal left inverted right x axis y axis)
    DFP4 disconnected (normal left inverted right x axis y axis)
    DFP5 disconnected (normal left inverted right x axis y axis)
    DFP6 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 473mm x 296mm
       1680x1050      60.0 +
       1400x1050      60.0* 
       1280x1024      60.0     75.0  
       1440x900       59.9  
       1280x960       60.0  
       1280x800       60.0  
       1280x768       60.0  
       1280x720       60.0  
       1024x768       75.0     60.0  
       800x600        75.0     60.3  
       640x480        75.0     59.9  
    DFP7 disconnected (normal left inverted right x axis y axis)
    CRT1 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
       1600x1200      60.0 +
       1400x1050      60.0* 
       1600x900       60.0  
       1280x1024      60.0  
       1440x900       59.9  
       1280x960       60.0  
       1366x768       59.8  
       1360x768       60.0  
       1280x800       59.8  
       1152x864       60.0  
       1280x768       59.9  
       1280x720       60.0  
       1024x768       60.0  
       800x600        60.3  
       720x480        60.0  
       640x480        59.9
    I've tried commands like:

    Code:
     xrandr --output DFP6 --mode 1024x768 --output CRT1 --mode 1024x768 --right-of DFP6
    And I get this: "xrandr: screen cannot be larger than 1680x1680 (desired size 2048x768)"

    What am I doing wrong?

  2. #2
    Join Date
    May 2008
    Beans
    214
    Distro
    Lubuntu

    Re: Can't get dual screen to work.

    xrandr detected the two monitor but for some reason the system thinks there is only one. Hows your xorg.conf?

    I was able to get my triple monitor working but just cant get the background to span on all three.

  3. #3
    Join Date
    Jun 2011
    Beans
    38

    Re: Can't get dual screen to work.

    Based on this topic: https://www.linuxquestions.org/quest...r-than-595649/ I tried to include "modes" and virtual in my /etc/X11/xorg.conf.fglrx-1, however after re-logging I never got anything but black screens. Now I've reloaded the original xonf and I've got a "AMD Unsupported Hardware" logo in the right hand corner.

    Code:
    Section "ServerLayout"	Identifier     "aticonfig Layout"
    	Screen      0  "aticonfig-Screen[0]-0" 0 0
    EndSection
    
    
    Section "Module"
    EndSection
    
    
    Section "Monitor"
    	Identifier   "aticonfig-Monitor[0]-0"
    	Option	    "VendorName" "ATI Proprietary Driver"
    	Option	    "ModelName" "Generic Autodetecting Monitor"
    	Option	    "DPMS" "true"
    EndSection
    
    
    Section "Device"
    	Identifier  "aticonfig-Device[0]-0"
    	Driver      "fglrx"
    	BusID       "PCI:1:0:0"
    EndSection
    
    
    Section "Screen"
    	Identifier "aticonfig-Screen[0]-0"
    	Device     "aticonfig-Device[0]-0"
    	Monitor    "aticonfig-Monitor[0]-0"
    	DefaultDepth     24
    	SubSection "Display"
    		Viewport   0 0
    		Depth     24
    	EndSubSection
    EndSection
    I've c/p'ed my conf as it is at the moment.

    Thanks.

  4. #4
    Join Date
    May 2008
    Beans
    214
    Distro
    Lubuntu

    Re: Can't get dual screen to work.

    Okay, a few things that we need to do:

    - We need to add Xinerama on your configuration.
    Section "ServerFlags"
    Option "Xinerama" "on"
    EndSection

    - Next, add this to your 'SubSection "Display" '
    Virtual 2048 2048

    - Finally, I just want to make sure, because sometimes it's the simplest thing that we forget to do. After editing your /etc/X11/xorg.conf.fglrx-1, did you rename it as "xorg.conf"?

    Hopefully, this works. If not, let us know. BTW, are you using one video card only?

  5. #5
    Join Date
    Jun 2011
    Beans
    38

    Re: Can't get dual screen to work.

    Are you sure about the 2048 2048 part? Seeing I have a 1080p and a 720p monitor which optimally should be running 1920x1080 and 1680x1050?

    I did not rename my .xorg.conf. Should I have?

    Yes, I am running with one video card only.

  6. #6
    Join Date
    May 2008
    Beans
    214
    Distro
    Lubuntu

    Re: Can't get dual screen to work.

    Well, basing on your xrandr command "xrandr --output DFP6 --mode 1024x768 --output CRT1 --mode 1024x768 --right-of DFP6", yes "virtual 2048 2048" should be fine. And yes, you should rename the file to xorg.conf. That is the file the system will look for. The other one is a backup created AMD when you tried to reconfigure your setup (AMD Catalyst Control Center perhaps).

    You can always change the virtual setting to a higher res later on. For now, at least try that if it works.

  7. #7
    Join Date
    Jun 2011
    Beans
    38

    Re: Can't get dual screen to work.

    Actually I do have a version of the Catalyst Control Center installed, however I seem to be unable to use it. I get a segment fault (core dumped) when I run it.

    Do you know how I verify which version I have of it?

    I'll definitely try your suggestion tonight when I get off from work. Thank you very much.

  8. #8
    Join Date
    Jun 2011
    Beans
    38

    Re: Can't get dual screen to work.

    Code:
    Hi again.
    
    So I tried to change the settings to the ones you suggested. At the moment my xorg.conf in X11 is looking like this:
    
    Section "ServerLayout"
        Identifier     "aticonfig Layout"
        Screen      0  "aticonfig-Screen[0]-0" 0 0
    EndSection
    
    
    Section "Module"
    EndSection
    
    
    Section "Monitor"
        Identifier   "aticonfig-Monitor[0]-0"
        Option        "VendorName" "ATI Proprietary Driver"
        Option        "ModelName" "Generic Autodetecting Monitor"
        Option        "DPMS" "true"
    EndSection
    
    
    Section "Device"
        Identifier  "aticonfig-Device[0]-0"
        Driver      "fglrx"
        BusID       "PCI:1:0:0"
    EndSection
    
    
    Section "Screen"
        Identifier "aticonfig-Screen[0]-0"
        Device     "aticonfig-Device[0]-0"
        Monitor    "aticonfig-Monitor[0]-0"
        DefaultDepth     24
        SubSection "Display"
            Viewport   0 0
            Depth     24
            Virtual 2048 2048
        EndSubSection
    EndSection
    
    Section "ServerFlags"
        Option "Xinerama" on
    Endsection
    If I've got the ServerFlags section on I just get two black screens at login. If I remove it while keeping the Virtual 2048 2048 I get in with who monitors that are identical and a xrandr -q that looks like this:

    Code:
    Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 2048 x 2048DFP1 disconnected (normal left inverted right x axis y axis)
    DFP2 disconnected (normal left inverted right x axis y axis)
    DFP3 disconnected (normal left inverted right x axis y axis)
    DFP4 disconnected (normal left inverted right x axis y axis)
    DFP5 disconnected (normal left inverted right x axis y axis)
    DFP6 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 473mm x 296mm
       1680x1050      60.0 +
       1400x1050      60.0* 
       1280x1024      60.0     75.0  
       1440x900       59.9  
       1280x960       60.0  
       1280x800       60.0  
       1280x768       60.0  
       1280x720       60.0  
       1024x768       75.0     60.0  
       800x600        75.0     60.3  
       640x480        75.0     59.9  
    DFP7 disconnected (normal left inverted right x axis y axis)
    CRT1 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
       1600x1200      60.0 +
       1400x1050      60.0* 
       1600x900       60.0  
       1280x1024      60.0  
       1440x900       59.9  
       1280x960       60.0  
       1366x768       59.8  
       1360x768       60.0  
       1280x800       59.8  
       1152x864       60.0  
       1280x768       59.9  
       1280x720       60.0  
       1024x768       60.0  
       800x600        60.3  
       720x480        60.0  
       640x480        59.9
    Any suggestions?

  9. #9
    Join Date
    May 2008
    Beans
    214
    Distro
    Lubuntu

    Re: Can't get dual screen to work.

    What kernel are you using?
    Terminal>uname -v

    Did you use the driver from Ubuntu?

    Look at /var/log/Xorg.0.log for some clue

    The reason I'm asking is because I had some trouble with kernel 3.8.0.25 but works just fine with 3.8.0.23. Also I used the driver I've downloaded from AMD. Now that will be up to you if you want to go that route . Lets first check your kernel version and for some clues.

  10. #10
    Join Date
    May 2008
    Beans
    214
    Distro
    Lubuntu

    Re: Can't get dual screen to work.

    By the way, you get the unsupported hardware logo because the driver is outdated for your card. That's the reason why I downloaded the driver from AMD.

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