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#1 2016-01-14 21:28:17

STREBLO
Member
Registered: 2015-02-15
Posts: 135

Screen Doubling with Displayport - Nvidia, MST 4K Monitor

I'm hoping someone else has figured out a solution to this problem but I've been unable to find a way to fix it myself.

I'm using a 4k TV as my monitor and up until now I was getting by using HDMI, however due to recent driver upgrades that broke my HDMI setup I am now unable to use HDMI at all with an updated driver. So I figured I'd give another look at trying to get DisplayPort working.

The issue I've been having is that when I use DisplayPort with a 4k monitor I end up with the screen thinking I'm using two different monitors due to MST (multi-stream transfer). This causes me to have two different backgrounds, and panels only reach half way across the screen. In addition to this when I open a new application it will end up getting opened in the center of one of the sides of my screen as it thinks that it is a monitor . The worst thing might also be the vertical screen tearing I'm getting in between the two virtual screens. I couldn't find anything in the arch wiki and I have messed around with xrandr but I can't seem to get anything that works.

Has anyone else figured out a way to get a unified display using a 4k monitor that uses MST?

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#2 2016-01-14 21:32:46

tom.ty89
Member
Registered: 2012-11-15
Posts: 608

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

Are you using some inappropriate xorg conf? This makes no sense to me. There is simply no reason for displayport to use MST (well, maybe for 3D?) for a single 4k monitor.

Last edited by tom.ty89 (2016-01-14 21:34:52)

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#3 2016-01-14 21:47:00

STREBLO
Member
Registered: 2015-02-15
Posts: 135

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

tom.ty89 wrote:

Are you using some inappropriate xorg conf? This makes no sense to me. There is simply no reason for displayport to use MST (well, maybe for 3D?) for a single 4k monitor.

It needs it because it it thinks of the screen as 2x 2k screens. My current xorg is fairly basic.

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

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#4 2016-01-14 21:51:08

tom.ty89
Member
Registered: 2012-11-15
Posts: 608

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

Maybe we can take a look at your xorg log and

xrandr --prop

to see if we can find any hint. Perhaps it's another bug of the nvidia driver?

FWIW, you probably don't need that xorg.conf and should get rid of it anyway.

Last edited by tom.ty89 (2016-01-14 21:51:49)

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#5 2016-01-14 22:51:51

STREBLO
Member
Registered: 2015-02-15
Posts: 135

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

tom.ty89 wrote:

Maybe we can take a look at your xorg log and

xrandr --prop

to see if we can find any hint. Perhaps it's another bug of the nvidia driver?

FWIW, you probably don't need that xorg.conf and should get rid of it anyway.

Screen 0: minimum 8 x 8, current 3840 x 2160, maximum 16384 x 16384
DVI-I-0 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: VGA 
                supported: VGA
        ConnectorType: DVI-I 
        ConnectorNumber: 0 
        _ConnectorLocation: 0 
DP-0.8 connected 1920x2160+0+0 (normal left inverted right x axis y axis) 349mm x 392mm
        GUID: {10DE9070-0005-2950-DDAC-6CA8000000D0}
        EDID: 
                00ffffffffffff0034a996a212800000
                00180104a58049780eee95a3544c9926
                0f505421080031404540614081800101
                0101010101010474801871705a80582c
                8a005d881100001e000000f7000a00c0
                80000000000000000000000000fc0050
                616e61736f6e69632d310a20000000fd
                00173d0f441e000a2020202020200271
                020319e144902022042309070168030c
                006000803c0fe2004b0474009880705a
                802c2c8a005d881100001e662156aa51
                001e30468f3300ba882100001e000000
                00000000000000000000000000000000
                00000000000000000000000000000000
                00000000000000000000000000000000
                00000000000000000000000000000065
                7012790000120016821000007f076f08
                000000000053544d9320020502050300
                14001d00c4ff0471016d002700cf021d
                0004000400030014001d00447f073d03
                7d022b0037042c000300040010010302
                05000000000000000000000000000000
                00000000000000000000000000000000
                0000000000000000000000000000a190
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: DisplayPort 
                supported: DisplayPort
        ConnectorType: DisplayPort 
        ConnectorNumber: 3 
        _ConnectorLocation: 3 
   1920x2160     60.00*+
   2048x2160     60.00  
   1920x1080     59.94    29.97    24.00    23.97  
   1366x768      59.79  
   1360x768      60.02  
   1280x1024     60.02  
   1280x768      59.99    59.87  
   1280x720      60.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.95    59.94  
DP-0.9 connected 1920x2160+1920+0 (normal left inverted right x axis y axis) 349mm x 392mm
        GUID: {10DE9070-0005-2950-DDAC-6CA8000000D0}
        EDID: 
                00ffffffffffff0034a996a212c00000
                00180104a58049780eee95a3544c9926
                0f505421080031404540614081800101
                0101010101010474801871705a80582c
                8a005d881100001e000000f7000a00c0
                80000000000000000000000000fc0050
                616e61736f6e69632d320a20000000fd
                00173d0f441e000a2020202020200230
                020315a1449020220468030c00700000
                3c0fe2004b0474009880705a802c2c8a
                005d881100001e662156aa51001e3046
                8f3300ba882100001e00000000000000
                00000000000000000000000000000000
                00000000000000000000000000000000
                00000000000000000000000000000000
                0000000000000000000000000000004d
                7012790000120016821010007f076f08
                000000000053544d9320020502050300
                14001d00c4ff0471016d002700cf021d
                0004000400030014001d00447f073d03
                7d022b0037042c000300040010010302
                05000000000000000000000000000000
                00000000000000000000000000000000
                00000000000000000000000000009190
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: DisplayPort 
                supported: DisplayPort
        ConnectorType: DisplayPort 
        ConnectorNumber: 3 
        _ConnectorLocation: 3 
   1920x2160     60.00*+
   2048x2160     60.00  
   1920x1080     59.94    29.97    24.00    23.97  
   1366x768      59.79  
   1360x768      60.02  
   1280x1024     60.02  
   1280x768      59.99    59.87  
   1280x720      60.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.95    59.94  
DVI-I-1 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: TMDS 
                supported: TMDS
        ConnectorType: DVI-I 
        ConnectorNumber: 0 
        _ConnectorLocation: 0 
HDMI-0 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: TMDS 
                supported: TMDS
        ConnectorType: HDMI 
        ConnectorNumber: 2 
        _ConnectorLocation: 2 
DP-0 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: DisplayPort 
                supported: DisplayPort
        ConnectorType: DisplayPort 
        ConnectorNumber: 3 
        _ConnectorLocation: 3 
DP-1 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: TMDS 
                supported: TMDS
        ConnectorType: DisplayPort 
        ConnectorNumber: 3 
        _ConnectorLocation: 3 
DVI-D-0 disconnected (normal left inverted right x axis y axis)
        BorderDimensions: 4 
                supported: 4
        Border: 0 0 0 0 
                range: (0, 65535)
        SignalFormat: TMDS 
                supported: TMDS
        ConnectorType: DVI-D 
        ConnectorNumber: 1 
        _ConnectorLocation: 1

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#6 2016-01-17 07:18:21

STREBLO
Member
Registered: 2015-02-15
Posts: 135

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

Every time I try a new setting with xrandr or twinview i'm getting half screens or crap. Anyone gotten a setting working to make two half screens appear as one?

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#7 2017-03-20 22:28:23

andrej.podzimek
Member
From: Zlín, Czech Republic
Registered: 2005-04-10
Posts: 85
Website

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

And more than a year later, the situation is still equally hopeless.
Tried hax11 (https://github.com/CyberShadow/hax11), but it doesn't really do anything, apart from making things much worse. (Screens are grouped randomly, some are inaccessible, chaos rules everywhere.)

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#8 2017-03-20 23:38:55

STREBLO
Member
Registered: 2015-02-15
Posts: 135

Re: Screen Doubling with Displayport - Nvidia, MST 4K Monitor

Yes at this point now HDMI works again but DisplayPort still gives double screens. There is a hack that combines them into one using:

Add the line:

Option "Xinerama" "1"
to your xorg.conf Section "ServerLayout".

However, it ends up breaking certain applications I noticed. I was using it for a long time, then it made Libre office and a few other applications stop working for some reason.

This isn't new technology but I guess it was only used for a short period of time and then abandoned for a superior implementation that doesn't use double screens.

Last edited by STREBLO (2017-03-20 23:41:48)

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