I have a Lenovo ThinkPad T400 (Montevina platform). The machine has switchable graphics capabilities. If the OS supports it (only Vista atm), the machine can switch between the onboard GMA X4500MHD and the dedicated ATI 3470 on the fly. Additionally, it's possible to choose between the two chips in the BIOS. When I boot with the ATI chip activated and fglrx or radeonhd as a driver, the external display is recognized on all three inputs (onboard VGA, VGA and DVI on the docking station). But when the Intel chip is enabled, the external display is only recognized if it's attached to the VGA port on the docking station. The system ignores it when attached at the onboard VGA port or the DVI port on the docking station. xrandr reports "VGA disconnected". Both Ubuntu 8.10 (xserver-xorg-video-intel 2.4.1-1ubuntu10) and Fedora 10 (not sure what version) show the same behavior. Please let me know which logs in which combination (Intel/ATI with radeonhd/fglrx/external VGA/internal VGA/external DVI) you need.
Please attach Xorg log (with ModeDebug yes set in xorg.conf) and xrandr output for intel/external DVI on Fedora 10.
Created attachment 20646 [details] Xorg.0.log with ModeDebug yes, external display attached to DVI
Created attachment 20647 [details] xrander --verbose, external display attached to DVI
according to what we known, this is a known HW design intention - integrated gfx only see LVDS and VGA, as you described.
Unfortunately, I don't have the time, hard disk space or license to install Windows on my machine to verify it, but according to some people (e.g. [1]), DVI works on XP/Vista when on the GMA chip. So, it that's true, the current state is clearly a regression compared to Windows. I'll look into getting a few more sources to verify that DVI does indeed work on Windows. I'm not sure what the policy here is about reopening bugs, so I'll leave it closed for the moment. [1] http://forum.thinkpads.com/viewtopic.php?p=470621#470621
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