I'm using T440s with a Thinkpad Ultra Dock and I'm also suffering from this bug.

I tried up to 3.14-rc1 plus "drm/i915: vlv: fix DP PHY lockup due to invalid PP sequencer setup" and still experiencing the problem.

A magic sysrq "Show Blocked State" shows the following blocked states:


[   94.401240] SysRq : Show Blocked State
[   94.401253]   task                        PC stack   pid father
[   94.401264] kworker/1:1     D ffff88031e252f80     0    35      2 0x00000000
[   94.401350] Workqueue: events ironlake_panel_vdd_work [i915]
[   94.401356]  ffff88030ffffd80 0000000000000046 ffff88030fc3c800 ffff88030fffffd8
[   94.401365]  0000000000012f80 0000000000012f80 ffff88030fc3c800 ffff880310272228
[   94.401373]  ffff88031027222c ffff88030fc3c800 00000000ffffffff ffff880310272230
[   94.401381] Call Trace:
[   94.401399]  [<ffffffff8164b9a9>] schedule_preempt_disabled+0x29/0x70
[   94.401408]  [<ffffffff8164d493>] __mutex_lock_slowpath+0x133/0x1b0
[   94.401416]  [<ffffffff8164d52f>] mutex_lock+0x1f/0x2f
[   94.401477]  [<ffffffffa0126f95>] ironlake_panel_vdd_work+0x25/0x40 [i915]
[   94.401487]  [<ffffffff810617e7>] process_one_work+0x177/0x420
[   94.401494]  [<ffffffff81062421>] worker_thread+0x121/0x3a0
[   94.401502]  [<ffffffff81062300>] ? manage_workers.isra.25+0x2b0/0x2b0
[   94.401511]  [<ffffffff810684f2>] kthread+0xd2/0xf0
[   94.401521]  [<ffffffff81068420>] ? kthread_create_on_node+0x180/0x180
[   94.401529]  [<ffffffff81656f6c>] ret_from_fork+0x7c/0xb0
[   94.401538]  [<ffffffff81068420>] ? kthread_create_on_node+0x180/0x180
[   94.401591] Xorg            D ffff88031e212f80     0  1569   1504 0x00400004
[   94.401600]  ffff8803027538c0 0000000000000086 ffff880300831800 ffff880302753fd8
[   94.401608]  0000000000012f80 0000000000012f80 ffff880300831800 ffffffff81e49c00
[   94.401616]  ffff8803027538f0 00000000ffff3747 ffffffff81e49c00 000000000000d0b8
[   94.401624] Call Trace:
[   94.401635]  [<ffffffff8164b539>] schedule+0x29/0x70
[   94.401644]  [<ffffffff8164a782>] schedule_timeout+0x162/0x2a0
[   94.401657]  [<ffffffff81051f00>] ? ftrace_raw_output_tick_stop+0x70/0x70
[   94.401715]  [<ffffffffa01279e8>] intel_dp_aux_ch+0x3b8/0x570 [i915]
[   94.401725]  [<ffffffff81087a30>] ? prepare_to_wait_event+0x100/0x100
[   94.401776]  [<ffffffffa0127c3a>] intel_dp_aux_native_write+0x9a/0xf0 [i915]
[   94.401825]  [<ffffffffa0128406>] ? intel_edp_psr_do_enable+0x186/0x2f0 [i915]
[   94.401875]  [<ffffffffa012a19f>] intel_dp_start_link_train+0x6f/0x2b0 [i915]
[   94.401926]  [<ffffffffa0123589>] intel_ddi_pre_enable+0x89/0xe0 [i915]
[   94.401974]  [<ffffffffa0113ee4>] haswell_crtc_enable+0xb4/0x620 [i915]
[   94.401983]  [<ffffffff81334949>] ? snprintf+0x39/0x40
[   94.402029]  [<ffffffffa011552f>] __intel_set_mode+0x85f/0x15c0 [i915]
[   94.402037]  [<ffffffff81334685>] ? vsnprintf+0x415/0x610
[   94.402085]  [<ffffffffa01186c6>] intel_set_mode+0x16/0x30 [i915]
[   94.402130]  [<ffffffffa0118f8b>] intel_crtc_set_config+0x7bb/0x990 [i915]
[   94.402175]  [<ffffffffa003f6ed>] drm_mode_set_config_internal+0x5d/0xe0 [drm]
[   94.402216]  [<ffffffffa0042547>] drm_mode_setcrtc+0xf7/0x5e0 [drm]
[   94.402247]  [<ffffffffa0033aa2>] drm_ioctl+0x4d2/0x600 [drm]
[   94.402263]  [<ffffffff811be15b>] ? inotify_handle_event+0xfb/0x150
[   94.402280]  [<ffffffff8118e8c8>] do_vfs_ioctl+0x2d8/0x4b0
[   94.402290]  [<ffffffff8117e511>] ? __sb_end_write+0x31/0x60
[   94.402298]  [<ffffffff8117c162>] ? vfs_write+0x172/0x1e0
[   94.402308]  [<ffffffff811989ef>] ? __fget_light+0x2f/0x70
[   94.402317]  [<ffffffff8118eb21>] SyS_ioctl+0x81/0xa0
[   94.402325]  [<ffffffff81657012>] system_call_fastpath+0x16/0x1b
[   94.402373] Sched Debug Version: v0.11, 3.14.0-rc1aha+ #2