Calibration of secondary X-screen

This topic has 18 replies, 2 voices, and was last updated 5 years, 2 months ago by Florian Höch.

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2019-01-17 at 13:09 #15280
Mark Bruurmijn
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Hello all,

I have configured a secondary screen using a xorg.conf file in Ubuntu 18.04. This was needed for an experimental setup using MATLAB and Psychtoolbox.

On the secondary screen, the mouse cursor is shown as a cross, and it is impossible to do anything on the screen. This is the desired behaviour, as normal users are not expected to do anything on this screen. However, it is therefore also impossible to color-calibrate the screen (using a Spyder 4), as it does not show up in the Ubuntu screen list or DisplayCAL and you cannot drag the window to the second screen either.

Is there a way to calibrate colors on the secondary screen?

Thanks in advance for your assistance!

Mark
2019-01-17 at 15:00 #15284
Florian Höch
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Hi,

I haven’t had to fiddle with Xorg conf files by hand for a long time – I would have expected the screen to be detected automatically when plugged in, and acting as a normal extended desktop by default.
2019-01-17 at 18:09 #15288
Mark Bruurmijn
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Hi Florian,

Thanks for your quick reply.

DisplayCAL does show two screen names, but it shows the main screen name twice. In Ubuntu’s screen setup, I only see the main screen.

Maybe I should mention that I use an NVIDIA NVS 315 graphics card and also the NVIDIA drivers (nvidia-driver-390, as MATLAB crashed on the Nouveau drivers). In the NVIDIA X-Server application, the screens do show up with their correct names.

Can this NVIDIA driver be the problem?
2019-01-18 at 18:45 #15299
Florian Höch
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Is this a “mirroring” configuration? Such would not be supported for calibrating and profiling.
2019-01-18 at 19:15 #15302
Mark Bruurmijn
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No, this is not a mirroring configuration.

I do find it a little strange that after the NVIDIA X-server setup (and writing the xorg.conf file), the second screen disappears from the ‘default’ screen devices list in Ubuntu Settings. Or is this normal?
2019-01-20 at 2:07 #15320
Florian Höch
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I would probably try to get rid of the proprietary binary nVidia driver completely and use noveau instead.
2019-01-22 at 13:39 #15368
Mark Bruurmijn
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Unfortunately, MATLAB still complains when using Nouveau drivers …

When starting DisplayCAL, I do see the second screen lighting up shortly, similar to the primary screen, so I guess both are detected by DisplayCAL. I only see the display name of the primary monitor twice in the list. Could this be a bug maybe?
2019-01-22 at 15:25 #15372
Florian Höch
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Configurations where screen coordinates are identical are also not supported (this is likely an Xorg or graphics driver bug, screen coordinates cannot overlap).
2019-01-22 at 18:00 #15399
Mark Bruurmijn
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I don’t think they overlap. Their position is specified using a ‘RightOf’-option.

Below is my xorg.conf file, generated by Psychtoolbox in MATLAB. Maybe you can notice something strange here.
```
# Auto generated xorg.conf - Created by Psychtoolbox XOrgConfCreator.

Section "ServerLayout"
Identifier "PTB-Hydra"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
EndSection

Section "Monitor"
Identifier "DP-4"
EndSection

Section "Monitor"
Identifier "DP-3"
EndSection

Section "Device"
Identifier "Card0"
Driver "nvidia"
Option "UseDisplayDevice" "DP-4"
Option "Monitor-DP-4" "DP-4"
Screen 0
EndSection

Section "Device"
Identifier "Card1"
Driver "nvidia"
Option "UseDisplayDevice" "DP-3"
Option "Monitor-DP-3" "DP-3"
Screen 1
EndSection

Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "DP-4"
Option "AllowHMD" "yes"
EndSection

Section "Screen"
Identifier "Screen1"
Device "Card1"
Monitor "DP-3"
Option "AllowHMD" "yes"
EndSection
```
2019-01-22 at 20:08 #15402
Florian Höch
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What are the screen coordinates?
2019-01-22 at 20:45 #15410
Mark Bruurmijn
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Hmm, the only thing I see about positioning (which I assume relates to the coordinates) is in the ServerLayout section:
```
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
```
I assumed that with the ‘RightOf’ property the screens were non-overlapping. Should I however include explicit coordinates somewhere? Should that then be in the ServerLayout, the Screens or the Monitors?

Sorry, I know close to nothing about Xorg :S Thanks for your patience!
2019-01-23 at 2:47 #15417
Florian Höch
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You can see the screen coordinates in DisplayCAL.
2019-01-23 at 10:38 #15426
Mark Bruurmijn
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DisplayCAL reports the same monitor twice, with the same coordinates. (See attached image.) I added explicit coordinates to the ServerLayout, the Screens and the Monitors, but that did not change anything, unfortunately.

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2019-01-23 at 22:12 #15433
Florian Höch
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That’s a configuration problem of the monitor setup, as I suspected. Overlapping coordinates are invalid. Normally, you really shouldn’t have to fiddle with Xorg config files. Does the graphical configuration interface not work?
2019-01-24 at 11:23 #15442
Mark Bruurmijn
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The Screens configuration in Ubuntu shows only one screen (the primary one). See also the attached screen shot.

I now created the xorg.conf file with the dedicated NVIDIA X Server. This conf file is more elaborate than the previous one, but the behaviour and the listing in DisplayCAL is the same.
```
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 390.77 (buildd@lcy01-amd64-022) Thu Sep 6 07:51:39 UTC 2018

Section "ServerLayout"
    Identifier "Layout0"
        Screen 0 "Screen0" 0 0
        Screen 1 "Screen1" RightOf "Screen0"
        InputDevice "Keyboard0" "CoreKeyboard"
        InputDevice "Mouse0" "CorePointer"
        Option "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "Module"
        Load "dbe"
        Load "extmod"
        Load "type1"
        Load "freetype"
        Load "glx"
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"
        # HorizSync source: edid, VertRefresh source: edid
        Identifier "Monitor0"
        VendorName "Unknown"
        ModelName "DELL P2317H"
    HorizSync 30.0 - 83.0
        VertRefresh 56.0 - 76.0
        Option "DPMS"
EndSection

Section "Monitor"
        # HorizSync source: edid, VertRefresh source: edid
        Identifier "Monitor1"
        VendorName "Unknown"
        ModelName "ESTECOM"
        HorizSync 30.0 - 80.0
        VertRefresh 55.0 - 76.0
        Option "DPMS"
EndSection

Section "Device"
        Identifier "Device0"
        Driver "nvidia"
        VendorName "NVIDIA Corporation"
        BoardName "NVS 315"
        BusID "PCI:1:0:0"
        Screen 0
EndSection

Section "Device"
        Identifier "Device1"
        Driver "nvidia"
        VendorName "NVIDIA Corporation"
        BoardName "NVS 315"
        BusID "PCI:1:0:0"
        Screen 1
EndSection

Section "Screen"
        Identifier "Screen0"
        Device "Device0"
        Monitor "Monitor0"
        DefaultDepth 24
    Option "Stereo" "0"
        Option "nvidiaXineramaInfoOrder" "DFP-2"
        Option "metamodes" "DP-4: 1920x1080 +0+0"
        Option "SLI" "Off"
        Option "MultiGPU" "Off"
        Option "BaseMosaic" "off"
        SubSection "Display"
                Depth 24
        EndSubSection
EndSection

Section "Screen"
        Identifier "Screen1"
        Device "Device1"
        Monitor "Monitor1"
        DefaultDepth 24
        Option "Stereo" "0"
        Option "nvidiaXineramaInfoOrder" "DFP-1"
        Option "metamodes" "DP-3: 1920x1080 +0+0"
        Option "SLI" "Off"
        Option "MultiGPU" "Off"
        Option "BaseMosaic" "off"
        SubSection "Display"
                Depth 24
        EndSubSection
EndSection
```
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