Comment 2 for bug 1782716

After that, it fails to recover:

 2372.712463] [drm:amdgpu_dm_atomic_check [amdgpu]] *ERROR* [CRTC:43:crtc-0] hw_done or flip_done timed out
[ 2538.367847] INFO: task kworker/u257:2:8785 blocked for more than 120 seconds.
[ 2538.367917] Not tainted 4.17.0-5-generic #6-Ubuntu
[ 2538.367968] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2538.368053] kworker/u257:2 D 0 8785 2 0x00000800
[ 2538.368067] Workqueue: events_unbound commit_work [drm_kms_helper]
[ 2538.368069] Call Trace:
[ 2538.368072] [c000000fcfb33460] [0000001400000000] 0x1400000000 (unreliable)
[ 2538.368078] [c000000fcfb33630] [c00000000001cd3c] __switch_to+0x2ec/0x4c0
[ 2538.368081] [c000000fcfb33690] [c000000000d42550] __schedule+0x330/0xa90
[ 2538.368083] [c000000fcfb33760] [c000000000d42cf0] schedule+0x40/0xc0
[ 2538.368086] [c000000fcfb33780] [c000000000d47b88] schedule_timeout+0x258/0x4f0
[ 2538.368090] [c000000fcfb33880] [c000000000923b90] dma_fence_default_wait+0x2b0/0x370
[ 2538.368093] [c000000fcfb338f0] [c000000000922f64] dma_fence_wait_timeout+0x74/0x190
[ 2538.368096] [c000000fcfb33930] [c000000000925fc0] reservation_object_wait_timeout_rcu+0x2f0/0x3e0
[ 2538.368141] [c000000fcfb339b0] [c00800000d10d108] amdgpu_dm_do_flip+0x130/0x3b0 [amdgpu]
[ 2538.368184] [c000000fcfb33b00] [c00800000d1113c8] amdgpu_dm_atomic_commit_tail+0xcb0/0xf90 [amdgpu]
[ 2538.368191] [c000000fcfb33c60] [c00800000c762b94] commit_tail+0x6c/0xe0 [drm_kms_helper]
[ 2538.368194] [c000000fcfb33c90] [c000000000137928] process_one_work+0x298/0x580
[ 2538.368197] [c000000fcfb33d20] [c000000000137c98] worker_thread+0x88/0x610
[ 2538.368200] [c000000fcfb33dc0] [c000000000140958] kthread+0x1a8/0x1b0
[ 2538.368203] [c000000fcfb33e30] [c00000000000b658] ret_from_kernel_thread+0x5c/0x84
[ 2659.214902] INFO: task kworker/u257:2:8785 blocked for more than 120 seconds.
[ 2659.214976] Not tainted 4.17.0-5-generic #6-Ubuntu
[ 2659.215019] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2659.215126] kworker/u257:2 D 0 8785 2 0x00000800
[ 2659.215141] Workqueue: events_unbound commit_work [drm_kms_helper]
[ 2659.215142] Call Trace:
[ 2659.215145] [c000000fcfb33460] [0000001400000000] 0x1400000000 (unreliable)
[ 2659.215151] [c000000fcfb33630] [c00000000001cd3c] __switch_to+0x2ec/0x4c0
[ 2659.215154] [c000000fcfb33690] [c000000000d42550] __schedule+0x330/0xa90
[ 2659.215157] [c000000fcfb33760] [c000000000d42cf0] schedule+0x40/0xc0
[ 2659.215160] [c000000fcfb33780] [c000000000d47b88] schedule_timeout+0x258/0x4f0
[ 2659.215163] [c000000fcfb33880] [c000000000923b90] dma_fence_default_wait+0x2b0/0x370
[ 2659.215166] [c000000fcfb338f0] [c000000000922f64] dma_fence_wait_timeout+0x74/0x190
[ 2659.215169] [c000000fcfb33930] [c000000000925fc0] reservation_object_wait_timeout_rcu+0x2f0/0x3e0
[ 2659.215217] [c000000fcfb339b0] [c00800000d10d108] amdgpu_dm_do_flip+0x130/0x3b0 [amdgpu]
[ 2659.215264] [c000000fcfb33b00] [c00800000d1113c8] amdgpu_dm_atomic_commit_tail+0xcb0/0xf90 [amdgpu]
[ 2659.215272] [c000000fcfb33c60] [c00800000c762b94] commit_tail+0x6c/0xe0 [drm_kms_helper]
[ 2659.215275] [c000000fcfb33c90] [c000000000137928] process_one_work+0x298/0x580
[ 2659.215278] [c000000fcfb33d20] [c000000000137c98] worker_thread+0x88/0x610
[ 2659.215281] [c000000fcfb33dc0] [c000000000140958] kthread+0x1a8/0x1b0
[ 2659.215284] [c000000fcfb33e30] [c00000000000b658] ret_from_kernel_thread+0x5c/0x84