Comment 128 for bug 1275794

I have exactly the same issue on Ubuntu 14.04 with an T440s which makes its display connection via the docking stations Display Port.

After I patched the Kernel with Stefan Agners link-train-delay.patch and now it works reasonably well, the time it takes to make the display connection for me is about 10 seconds at max, which is acceptable for me.

However, I don't think this solution is perfect, so I added a few dollars to the bounty and hope some working patch makes it upstream.