[Bug 89589] [dp mst] External displays remain blank with linux-3.18.6 after resuming from suspend

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=89589

--- Comment #19 from Chris Salzberg <chrissalzberg at gmail.com> ---
Just another "me too". I see this with two monitors (DP1-1 & DP1-2) attached
via mdp + laptop (eDP1).

My kernel: 4.2.5-1-ARCH #1 SMP PREEMPT Tue Oct 27 08:13:28 CET 2015 x86_64
GNU/Linux

When I resume from sleep the laptop monitor comes on but the other two do not.
If I turn off one of them the other comes back, and then I can turn the other
one on. But I've found the state then to be unstable and the system can freeze
suddenly so I tend just not to put it to sleep with both monitors attached.

Not sure if it's related but I see this flagged in journalctl:

drm:intel_mst_pre_enable_dp [i915]] *ERROR* failed to allocate vcpi
drm:intel_mst_enable_dp [i915]] *ERROR* Timed out waiting for ACT sent
drm:intel_mst_pre_enable_dp [i915]] *ERROR* failed to allocate vcpi
drm:intel_mst_enable_dp [i915]] *ERROR* Timed out waiting for ACT sent
-----------[ cut here ]------------
ARNING: CPU: 2 PID: 18078 at drivers/gpu/drm/i915/intel_display.c:6380
intel_modeset_check_stat
rong connector dpms state
odules linked in: rfcomm ctr ccm fuse xt_conntrack ipt_MASQUERADE
nf_nat_masquerade_ipv4 iptabl
snd_soc_rt5640 cfg80211 hid_generic snd_soc_rl6231 bluetooth hid_logitech_dj
media snd_soc_core
aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd ahci libahci libata
ehci_pci xhci_pci sc
PU: 2 PID: 18078 Comm: kworker/u16:92 Not tainted 4.2.5-1-ARCH #1
ardware name: Dell Inc. XPS13 9333/0D13CR, BIOS A05 09/11/2014

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