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Problem with a DVI + HDMI combination

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  • Problem with a DVI + HDMI combination

    Hi everyone.

    I'm having lots of trouble with a very simple setup (kernel, libdrm, radeon and other stuff are all rather recent from git).

    I'm using an HD 4550. I have a main 1920x1080 monitor as DVI-0. On its own, it works perfectly. The trouble starts when I plug in a Samsung 1280x720 TV as HDMI-0.

    First of all, the only common resolution they have is 640x480, which is what KDM uses. It's selected regardless of whether the TV is on or off, as it reads it via HDMI. It's not only ugly, but it keeps this resolution after logging in. Then I have to do "xrandr --output HDMI-0 --off" and "xrandr -s 1920x1080" and resize all the panels which were not designed for 640x480. Very annoying, since I only want to use the TV occasionally for watching a movie.

    I've tried solving it by putting the relevant xrandr calls into /usr/share/config/kdm/Xsetup, but this didn't work well (right resolution, wrong DPI, and a tiled 640x480 wallpaper).

    The current solution is the manually plug and unplug the HDMI cable based on whether I need to use the TV, which works fine once KDE and X are up and running, but can't be the long-term solution.

    Any hints?

    How can I get a 1920x1080 framebuffer console at boot, like I do with a single monitor? How can I switch off the HDMI-0 output BEFORE kdm starts, so it can set the native resolution of my main monitor instead of 640x480?

  • #2
    I had similar trouble: two monitors + projector connected. Only two can be active at any time, but the projector is detected as on even when I yank the power cord.

    I've added this to my /usr/kde/3.5/share/config/kdm/Xsetup
    xrandr --output DFP2 --off
    xrandr --output DFP4 --off
    xrandr --output DFP3 --primary --mode 1920x1200 --pos 0x0
    xrandr --output DFP4 --mode 1600x1200 --right-of DFP3
    there's a similar file for kde4, probably in /usr/share/..

    no idea about the framebuffer consoles.


    • #3

      That's roughly what I did, and it works OK (even the DPI and thus font size is ok), but kdm still shows a 640x480 login screen, but tiled to fill 1920x1080.

      Could this be a kdm problem?


      • #4
        that does sound weird. If you remove all further xrandr-commands from your login-settings, does the tiling persist after login?

        I can only tell you that everything works as expected with kde 3's kdm.


        • #5
          The tiling is gone as soon as the KDE splash screen shows up. It's quite likely that

          - it's a kdm bug, or
          - there's a kdm option I can set somewhere


          • #6
            If anyone is interested, this is what is in my /usr/share/config/kdm/Xsetup:

            xrandr --output HDMI-0 --off
            xrandr --output DVI-0 --primary --mode 1920x1080 --pos 0x0
            xrandr --output HDMI-0 --mode 1280x720 --right-of DVI-0 --set underscan off
            At the moment, I turn on cloning of displays when the TV is off, so my screen edges work properly, and I turn off cloning when I want to watch something on the TV. Works OK.