Dell P2715Q Monitor does not wake up after sleep (off, standby, or suspend)

[Thomas Lübking]

On Wed, Aug 09, 2017 at 11:39:06AM -0400, Greg Gorsuch wrote:
>Where are the sleep logistics handled? Is it with the X server, the NVIDIA
>drivers, the Linux Kernel, or somewhere else? Is it possible to capture the
>communications on Windows 10 to identify how it is being handled. I don't
>get the feeling it should be that complex to fix or at least implement a
>work around since xrander is able to bring the monitor back online.

It sounds like when you go dpms off, the monitor unregisters and when
you go dpms on, the monitor re-registers.
Then some semi-smart randr daemon kicks in and adjusts the layout, but
does not so when the monitor comes back.

Try to log the setup in the various modes:

xset dpms force standby; sleep 10; xrandr --current > ~/randr.standby;
xset dpms force suspend; sleep 10; xrandr --current > ~/randr.suspend;
xset dpms force off; sleep 10; xrandr --current > ~/randr.off; xset
dpms force on

Also try the behavior on a "naked" X11 server (no desktop session, only
an xterm) to see whether some client or the server adjusts the randr setup.

Cheers,
Thomas