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Developer in me woke up this morning and asked me to fix this before Christmas. (As his Christmas gift).

So, if I power on the laptop after docking it, everything works fine. But if I am working on it standalone and then try to dock it, I cannot get the display. Same way, if I undock it while working, I loose the display.

Basically, I need to reboot for any docking/undocking dance to work.

Questions: 1) What kind of information should I be looking for to understand the problem? 2) Where to find that information.

After this, I can go and try to figure out what is going wrong.

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No takers? Marry X'mas. – hari Dec 25 '10 at 5:32
Santa is not happy this year - I guess. Thanks anyways. – hari Jan 3 '11 at 18:51
Sorry - not an answer only a seconding. As a matter of fact, suspend and resume on the t400 seems broken more often than working correctly – TheSteve0 Jan 26 '11 at 5:34
The problem is not specific to T400. I have a Dell Inspiron D830 with a D-Port and facing the same issue. Even the keyboard/mouse is sometimes lost in addition to the display when hot (un)docking. I guess this has something to do with X server configuration not being refreshed. – wigy Jul 6 '11 at 12:38
up vote 2 down vote accepted

I have a similar experience with T400 and dock station (ThinkPad Port Advanced Mini Dock). I'm using Fedora 14 and the Intel graphics (Radeon switched off in BIOS, as both the proprietary and open the driver has issues in dual screen mode).

When I undock with the laptop running, usually the laptop is still usable. The later dock-in operation is not 100% successful, e.g. the usb mouse connected to the docking station is no more working till the next re-boot.

To be honest, I'd be happy if I could at least suspend to disk - undock - resume - suspend to disk - dock in - resume, but this cycle has just about 30-50% success - which is a real pain. So result is that unplugging few more cables is much faster then waiting for re-boot and opening all the docs closed before the shutdown :-(

Concerning the hot undock-dock, I have tried the howto on

The shell script works well, after some customization, but udev rule

KERNEL=="dock.0", ACTION=="change", RUN+="/usr/local/sbin/"

does not trigger it.

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something is better than nothing :-) thank you – hari Nov 28 '12 at 20:36

Hiya, from my own experience in any additions to computers I would personally save all my work and shut down the computer to ensure all your hard work is saved and will not be affected. Unlock your computer and eject from the docking station. Once fully ejected you can then restart your computer in the normal waysafe in the knowing that nothing will be damaged or lost. I would always use this procedure also when placing back into the dock. Shut down first, connect to the dock and then restart.

For more information check out

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This is not the answer but still thanks. – hari Jan 3 '11 at 18:50

The T400 has switchable graphics, meaning it has a choice of two different GPUs (Intel and Radeon). You can force it to only use the Radeon from the BIOS settings by selecting "Discrete Graphics".

Only the Radeon is physically connected to the docking port.

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On my T520, the VGA output on the docking station is connected to the integrated graphics. – codeape Feb 4 '13 at 9:11

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