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Thread: xrandr - screen resolution - 2nd screen

  1. #1
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    xrandr - screen resolution - 2nd screen

    So I on my laptop I have a custom external screen and when it comes on it has a crazy big screen resolution of 2048x1536 and that is the only mode it has in xrandr,

    Well I followed this how-to trying to get it to be close to my laptops screen resolution.

    https://askubuntu.com/questions/3779...tom-resolution

    But when I do that it come out like this,


    I am not new to linux but I am new to xubuntu so I haven't ever seen this before I figured maybe someone else has.

    Last edited by Caleb.Robertson; 1 Week Ago at 01:59 PM.

  2. #2
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    Re: xrandr - screen resolution - 2nd screen

    For changing EDID/monitor provided resolutions, I like the lxrandr GUI tool. EDID is how monitors have provided their capabilities to GPUs for a very long time, at least 15 years, since the VGA days. HDMI, DVI, and DP support this too.

    If you need to override the resolutions (called "modes" in X11), then manually creating an xorg.conf file will be needed. Looking up the native resolution, refresh rates, horizontal and vertical sync rates will be needed. That data goes into the "modeline". There are examples of X11 config files on the internet. I can post one of mine, but yours WILL be different and must be customized for the GPU, monitors, settings. Copy/paste will not work.

    I have know idea how Wayland does it. None. Sorry.

    Perhaps someone else knows how to get the EDID information to work. I've had to manually dump it because a DVI-i -to- VGA adaptor didn't pass it on to the GPU. Previously, the system was using a VGA KVM without any issues, but the new GPU doesn't support VGA.

  3. #3
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    Re: xrandr - screen resolution - 2nd screen

    Thank you for your reply I will try tonight when I get home.

    If it helps this is the LCD to DisplayPort Adapter I used
    http://abusemark.com/store/index.php...products_id=47

    After thinking about it I am pretty sure that the resolution is hard wired into the adapter...considering it is printed on the board. I just haven't ever heard of a driver not accepting a lower resolution. Ill do some testing and report back.
    Last edited by Caleb.Robertson; 1 Week Ago at 08:17 PM.

  4. #4
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    Re: xrandr - screen resolution - 2nd screen

    So I tried lxrandr and now luck, I am not very good at making an xorg.conf from scratch I have really only done it with nvidia drivers.

    Is there a way you could post yours and I can edit it from there?

    Also I contacted the manufacturer and asked them if what I am trying is even possible.

  5. #5
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    Re: xrandr - screen resolution - 2nd screen

    Here's a modeline:
    Code:
    Section "Monitor"
    ....
       Modeline "1280x1024"  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync 
    ....
    EndSection
    See why you'll need all the technical details before starting? That's 1 of 12 versions and the settings were provided by the monitor using an EDID dump program. From the EDID, you can find a tool to make the modelines.

    Overview of the steps:
    * directly connect the monitor and some Linux computer.
    * use a edid dump program to get the raw/binary information
    Code:
    $ man -k edid
    get-edid (1)         - read-edid tools to retrieve and interpret monitor spec...
    parse-edid (1)       - read-edid tools to retrieve and interpret monitor spec..
    * move that dumped data in a file to the other computer
    * figure out how to have the GPU use the edid file information, not whatever some adaptor is seeing:
    Code:
    Section "Device"
    ...
        Option "UseDisplayDevice" "DFP-0"
        Option "CustomEDID" "DFP-0:/etc/X11/xorg-monitor.dell-2412m.edid.raw"
    ...
    EndSection
    Check the /var/log/Xorg.0.log for errors and fix those.

    I have doubts any of this will help with that converter.

  6. #6
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    Re: xrandr - screen resolution - 2nd screen

    Welp what I am trying to do is apparently not possible per the manufacture. I guess we can close this, thank you for your help.

    Here is the reply i got from them.
    Hi there,

    There is no "scaler" on that board, it will only support native panel resolution of 2048x1536.
    Which is why it requires DisplayPort input.


    Regards


  7. #7
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    Re: xrandr - screen resolution - 2nd screen

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