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Odd 1024x768 Autodetection

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  • Odd 1024x768 Autodetection

    I have a ThinkPad T400 with a GMA 4500MHD. If I don't have a xorg.conf file, the resolution is detected at 1024x768, when I have a 1400x900 display. Also, closing the lid for longer than about seven seconds also causes it to switch to this resolution. Repeating this action causes the resolution to revert back to 1440x900. This happens with both DDX 2.8.0 and 2.8.1, kernel, Mesa 7.5.1, and X Server 1.6.3.

  • #2
    Is there an additional connector regarding video output connected? Dockingstation, DVI, HDMI, VGA connected even if not used?

    The reason why I ask is because the intel driver does this during initialization:
    (II) intel(0): Using fuzzy aspect match for initial modes

    Basically it uses the highest resolution that all attached devices share in their EDID. This is described in more detail in section "Initial Mode Selection" of keith' blog:

    Detecting connected monitors is fine, but one thing we haven’t really solved is what to do when you have more than one connected when the server starts. My initial code would pick one ‘primary’ monitor, light that up at its preferred size and then pick modes for the other monitors which were as close as possible to the primary monitor size without being larger. Obviously, I liked that as it meant my laptop always came up looking correct on the LVDS and my external VGA would show most of the screen.

    However, this was reported to confuse a lot of users. I can imagine that starting the X server with one of the outputs connected but not turned on would make for some ‘interesting’ support calls. So, now the X server picks a mode which all outputs can support and uses that everywhere. Sadly, this means that my laptop panel gets some random scaled mode (usually 1024x768) which looks quite awful.

    I think we need something better than either of these choices, but I’m not quite sure how it should work.

    But maybe you have a different issue.


    • #3
      You should probably report this as a bug:


      • #4
        I think 7oby is on track. You probably have additional outputs which are not being used or are not even fully implemented.

        Get a list of video outputs with "xrandr -q"

        I have a 945GME chipset on a mini-ITX mobo, and I had outputs showing up for DVI, LVDS, VGA and TV, even though the LVDS was not implemented. You can knock those out by putting ignores in the xorg.conf file:

        Section "Monitor"
        Identifier "LVDS1"
        Option "Ignore" "TRUE"


        • #5
          As far as I remember there are plenty TV-out and LDVS quirks added to the intel driver when discovering those "ghost" video connectors. Just something I googelt quickly:

          Once you figured the display channel that causes these problems and temporarily disabled it in xorg.conf according to man pages or CrystalCowboy's instructions, you may post your strings to the intel devs to include and test a fix in the driver.