This has worked to re-display my screen power is removed and then
re-applied to the monitor, I'm doing further testing to see if it also
fixes the issue with lockscreen blanking and sleeping.

On Thu, May 19, 2016 at 8:25 AM, Jan <email address hidden> wrote:
> Please try the patch mentioned here:
> https://bugs.launchpad.net/bugs/1308105
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1581302
>
> Title:
>   Monitor remains blanked with Intel Graphics
>
> Status in lightdm package in Ubuntu:
>   Confirmed
>
> Bug description:
>   Running on a NUC5i7RYH, latest BIOS. ASUS Monitor connected via Display Port or HDMI
>   Running Xubuntu 16.04 - latest all current patches
>
>   Sometimes the monitor remains blanked even when the session has
>   reactivated.
>
>   I have been able to reproduce this problem by letting the monitor
>   remain in the 'blanked' state for > 60 minutes, or powering off the
>   monitor. When the monitor is powered back on and the session is woken
>   up with mouse or keyboard input, it does wake up but the monitor
>   remains blanked.
>
>   I was able to prove to myself the session was awake by leaving it with
>   terminal opened to full screen with VIM running on an NFS mounted file
>   system. I could type and save at the black monitor screen and see that
>   the file got updates from a different system. So the session is "live"
>   but the computer has forgotten to re-establish the DisplayPort link.
>
>   An error appears in the lightdm logs about setting a CRTC, if you
>   activate an alternate terminal (say with CTL-ALT-F1) and try `xrandr
>   --output DP1 --auto` it also registers that CRTC error. HOWEVER, if
>   you ssh in from a different machine, tell bash to export DISPLAY=:0
>   (set $DISPLAY to ':0') and then type 'xrandr --output DP1 --auto' the
>   screen turns on again! This also happens on a Gigabyte BRIX system
>   (same NUC reference design but in that case a core i3 rather than a
>   Core i7).
>
>   To reproduce, turn off the monitor, wait an hour, and turn it on
>   again.
>
>   You can also kill HUP the lightdm process and that will restart a new
>   session (but open windows in the previous session are lost).
>
>   So interesting questions, why does typing xrandr "locally" give you
>   the error but running it from an ssh session work?
>
>   Since xrandr and restarting the session can both "fix" the problem,
>   the driver seems to know how to turn the display on if told correctly.
>
>   How can I find out where the code is getting the CRTC error?
>
>   ProblemType: Bug
>   DistroRelease: Ubuntu 16.04
>   Package: lightdm 1.18.1-0ubuntu1
>   ProcVersionSignature: Ubuntu 4.4.0-22.39-generic 4.4.8
>   Uname: Linux 4.4.0-22-generic x86_64
>   ApportVersion: 2.20.1-0ubuntu2
>   Architecture: amd64
>   CurrentDesktop: XFCE
>   Date: Thu May 12 20:33:01 2016
>   InstallationDate: Installed on 2016-05-08 (4 days ago)
>   InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
>   LightdmDisplayLog: (II) AIGLX: Suspending AIGLX clients for VT switch
>   LightdmLog:
>    [+80180.09s] DEBUG: Seat seat0 changes active session to
>    [+80189.53s] DEBUG: Seat seat0 changes active session to 64
>    [+80222.67s] DEBUG: Seat seat0 changes active session to c4
>    [+80222.67s] DEBUG: Session c4 is already active
>   SourcePackage: lightdm
>   UpgradeStatus: No upgrade log present (probably fresh install)
>
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