x11: Primary monitor goes black randomly

Perry Hutchison perryh at pluto.rain.com
Fri Jul 15 08:14:12 UTC 2016

Rares Vernica <rvernica at gmail.com> wrote:
> I am using an HP Elitebook 2560p which has an integrated Intel video card.
> I use two external monitors, one connected on the DisplayPort as primary
> and one on the VGA port as secondary. I am not using the built-in display.
> I use x11 with xfce and the Intel driver. It all works fine, except that
> the the primary monitor (on the DisplayPort) goes black at random times.
> Once black, the monitor reports no signal and goes on stand by. It does
> not resume working if I move the mouse or type on the keyboard. One way I
> managed to recover it is to turn the display off with xrandr and then back
> on.

I suspect this is an x11 problem, not a FreeBSD problem.

I have been seeing something similar on a Dell laptop, using gnome,
with the built-in display as primary and an external 1920x1080
flatscreen on a DVI port (on the docking station) as secondary.
The primary occasionally goes blank just after logging in (via xdm),
about the time when xrandr would be setting up the dual screens,
and the only way I've found to bring it back is to tweak the screen
positions slightly in gnome-control-center (which then presumably
runs xrandr when I click Apply).  I suspect a race condition since
it happens only occasionally.

So why do I think this is not a FreeBSD issue?  Because it happens
on Fedora Linux (at $DAYJOB).

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