I have an embedded system with armv71 and Ubuntu 16.04. It has only a touchscreen (so no mouse or keyboard attached) and runs Chromium in kiosk mode, without a desktop (only X and openbox).
As the screen listens to DPMS settings, in xorg.conf I have a BlankTime set of 60 minutes. Anything else (standby, suspend, off) fails, as the touch driver doesn't respond anymore when the screen is off. And since there is no other device attached, I cannot wake up the machine.
The problem is that blanking the screen doesn't turn off the backlight. After al lot of searching I found that when typing
echo "0" > /sys/class/pwm-sunxi/pwm0/duty_percent
the backlight responds and turns off. A value of 30 turns it on again.
But I can't find anything to pair the backlight to the blanktime. So the question is: is there any way to turn off the backlight when the BlankTime triggers, and change it back again when screen blanking turns off?
My xorg.conf:
Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Screen0" 0 0
EndSection
Section "ServerFlags"
Option "BlankTime" "60"
Option "StandbyTime" "0"
Option "SuspendTime" "0"
Option "OffTime" "0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Allwinner A10/A13 FBDEV"
Monitor "Monitor0"
DefaultDepth 24
Subsection "Display"
Depth 24
Modes "1280x800p60"
EndSubsection
EndSection
Section "Device"
Identifier "Allwinner A10/A13 FBDEV"
Driver "sunxifb"
Option "fbdev" "/dev/fb0"
Option "AccelMethod" "G2D"
Option "SwapbuffersWait" "true"
EndSection
Section "Monitor"
Identifier "Monitor0"
Vendorname "Unknown"
Modelname "Unknown"
HorizSync 30.0 - 83.0
VertRefresh 43.0 - 76.0
Option "DPMS"
Modeline "1280x720p50" 60.74 1280 1328 1456 1632 720 721 724 741 -HSync +Vsync
Modeline "1280x800p60" 83.46 1280 1344 1480 1680 800 801 804 828 -HSync +Vsync
Option "DPMS" "true"
EndSection
