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View Full Version : [lubuntu] Blank display when attached after boot



jonathan74
March 9th, 2015, 05:26 AM
Hi all,

I'm using Lubuntu as the base for a digital signage platform. The problem I'm having is with being able to attach a display after the system has already booted. The display remains blank. I've spent a few hours trying to figure this out, and I'm wondering if anyone has some ideas.

OS: Lubuntu 14.04
Displays: Dell U2711 (27" LCD) and a standard LG 32" TV both give the same result
Hardware: Intel Atom NUC DE3815TYKHE, connected to the screen via HDMI. I've configured the BIOS to always use HDMI.

The system works fine as long as the display is plugged in turned on at startup.

I've tried configuring the display with gtf and xrandr with no success. I can control it if it's been plugged in at startup, but not otherwise:


if [ ! -t 0 ]
then
gtf 1920 1080 60
xrandr --newmode Manual1 172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync
xrandr --addmode HDMI1 Manual1
xrandr --output HDMI1 --mode Manual1
fi


Here is the output of xrandr when the display is plugged in. This same output also appears once the display has been plugged in, after being unplugged on startup.



user@hostname:~$ DISPLAY=:0 xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 32767 x 32767
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 1600mm x 900mm
1920x1080 60.0*+ 50.0 59.9 30.0 25.0 24.0 30.0 24.0
1920x1080i 60.1 50.0 60.0
1280x1024 60.0
1360x768 60.0
1152x864 60.0
1280x720 59.8 60.0 50.0 59.9
1440x576i 50.1
1024x768 60.0
800x600 60.3
720x576 50.0
720x480 60.0 59.9
640x480 60.0 59.9 59.9
720x400 70.1
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)


Can anyone shed some light on how to always supply a signal for HDMI1 even if the display is not plugged in?

Thanks in advance.

jonathan74
March 26th, 2015, 03:30 AM
Bump.