blank screen after lock screen.

[Hacksign]

Archlinux + awesome + lightdm + lightdm-gtk-greeter

1. login to system.
2. lockscreen with 'dm-tool lock' command
3. active screen and unlock system
4. lockscreen with 'dm-tool lock' agian

result:
can not light up screen.
can not switch tty witch hotkey 'ctrl+alt+F1'
this happens every time if I lock screen twice

there is a failure in Xorg.0.log:
[root at XSign log]# cat Xorg.0.log|grep fail -A1 -B1
[     3.411] xf86: remove device 0 
/sys/devices/pci0000:00/0000:00:02.0/drm/card0
[     3.411] failed to find screen to remove
[     6.538] (II) config/udev: Adding input device TPPS/2 IBM TrackPoint 
(/dev/input/mouse1)

[root at XSign log]# uname -an
Linux XSign 4.4.5-1-ARCH #1 SMP PREEMPT Thu Mar 10 07:38:19 CET 2016 
x86_64 GNU/Linux

[root at XSign log]# lspci -v
00:02.0 VGA compatible controller: Intel Corporation Broadwell-U 
Integrated Graphics (rev 09) (prog-if 00 [VGA controller])
     Subsystem: Lenovo Device 2227
     Flags: bus master, fast devsel, latency 0, IRQ 46
     Memory at f0000000 (64-bit, non-prefetchable) [size=16M]
     Memory at e0000000 (64-bit, prefetchable) [size=256M]
     I/O ports at 3000 [size=64]
     Expansion ROM at <unassigned> [disabled]
     Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
     Capabilities: [d0] Power Management version 2
     Capabilities: [a4] PCI Advanced Features
     Kernel driver in use: i915
     Kernel modules: i915

[root at XSign log]# pacman -Q|grep xf86-video
xf86-video-intel 1:2.99.917+622+gde44aaa-1


Is it a but or an uncorrect config wich caused this problem ?