[Bug 66211] New: Thinkpad T440s with 2nd screen via dock freezes

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=66211

            Bug ID: 66211
           Summary: Thinkpad T440s with 2nd screen via dock freezes
           Product: Drivers
           Version: 2.5
    Kernel Version: 3.12
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - Intel)
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: madevr.orange at gmail.com
                CC: intel-gfx-bugs at lists.freedesktop.org
        Regression: No

Hi there.

There seems to be a problem with using a 2nd screen via dock on the Thinkpad
T440s. I have the version with Intel HD4400 only, but users with additional
dedicated graphics also report this (though Intel seems to be the cause).

Steps to reproduce:
1) Power off Thinkpad T440s, connect 2nd screen to dock, put Thinkpad into
dock.
2) Boot Thinkpad: both screens stay black.

or

1) Power on Thinkpad, leave it on and connect 2nd screen to dock
2) Put Thinkpad into dock - the system freezes, 2nd screen shows no image.

In both cases the system can be unfrozen by undocking.

Connecting a 2nd screen directly to the Thinkpad works as intended.

Apparently more users start to experience this problem:
https://bbs.archlinux.org/viewtopic.php?id=173134

I am completely new to reporting kernel bugs but am eager to help solving this
problem. Let me know how I can help. ;)

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