Comment 24 for bug 1320282

Flashing the recent BIOS update (FBKTA5A released 2015-01-06) resolved the problem for me:
http://support.lenovo.com/downloads/ds035753
Shutdown works now with kernel 3.13.0-44.

As I did a bisect from 3.13.0-43 to 3.13.0-44 before I did the BIOS update here's the result anyway:

01414f897d20874f6f5d7ef2f756f5bf2df526fc is the first bad commit
commit 01414f897d20874f6f5d7ef2f756f5bf2df526fc
Author: Denis Turischev <email address hidden>
Date: Tue May 20 14:00:42 2014 +0300

    xhci: Switch only Intel Lynx Point-LP ports to EHCI on shutdown.

    BugLink: http://bugs.launchpad.net/bugs/1402853

    commit 0a939993bff117d3657108ca13b011fc0378aedb upstream.

    Patch "xhci: Switch Intel Lynx Point ports to EHCI on shutdown."
    commit c09ec25d3684cad74d851c0f028a495999591279 is not fully correct

    It switches both Lynx Point and Lynx Point-LP ports to EHCI on shutdown.
    On some Lynx Point machines it causes spurious interrupt,
    which wake the system: bugzilla.kernel.org/show_bug.cgi?id=76291

    On Lynx Point-LP on the contrary switching ports to EHCI seems to be
    necessary to fix these spurious interrupts.

    Signed-off-by: Denis Turischev <email address hidden>
    Reported-by: Wulf Richartz <email address hidden>
    Cc: Mathias Nyman <email address hidden>
    Signed-off-by: Greg Kroah-Hartman <email address hidden>
    Signed-off-by: Kamal Mostafa <email address hidden>

:040000 040000 2017c75e797dd6fde9e00f73db85fa32eeb19775 7d11924d8262e57dab18920cf19ec4c14e93db5f M drivers