I also ran into this with a Thinkpad T440 and an Ultra Dock.
I tried the patch in Comment 11 as well as changing the udelay(100) to udelay(500), that Comment 29 mentioned. Didn't change anything: As soon as I plug a monitor via VGA or DVI in the dock, the screen freezes and returns to normal on undocking.
I would be happy to supply further information, if you tell me what you need.
I also ran into this with a Thinkpad T440 and an Ultra Dock.
I tried the patch in Comment 11 as well as changing the udelay(100) to udelay(500), that Comment 29 mentioned. Didn't change anything: As soon as I plug a monitor via VGA or DVI in the dock, the screen freezes and returns to normal on undocking.
I would be happy to supply further information, if you tell me what you need.