LCD backlight remains off

[Matteo Croce]

After an inactivity timeout, the screen backlight is powered off, but on activity (mouse, keystroke, etc)
the lamp is not switched on.

In the dark screen I can barely see the login page, and if I login, with the help of a torch I can turn the light on via the systray icon,
or via SSH from another machine writing to /sys/class/backlight/intel_backlight/brightness

Bug is in Ubuntu 15.04 and Ubuntu 15.10

[Vladi Gergov (vladi-1)]

I have to use xbacklight -inc 100 to turn my backlight on my laptop after prolonged lcd sleep.

Reproducible: Sometimes

Steps to Reproduce:
1. let kde go to power save mode
2. wake up using mouse
3. no backlight

Actual Results:
no backlight for my laptop screen

Expected Results:
backlight for my laptop screen

if I have a monitor pluged in it does come on just not my laptop screen.

[Matteo Croce (teknoraver)]

Happens to me too, VERY annoying

[Matteo Croce (teknoraver)]

Created attachment 95043
how to fix

This is how I have to enable the backlight again every time, using a torch

[Matteo Croce (teknoraver)]

Created attachment 95044
how to fix

[Matteo Croce (teknoraver)]

Created attachment 95045
login

SDDM is active, I can login by typing blindly

[Vladi Gergov (vladi-1)]

do you have a intel video card? What kernel?

[Vladi Gergov (vladi-1)]

Created attachment 95609
emerge --info

[Vladi Gergov (vladi-1)]

one more data point, seems that when I plug / unplug my charger cable it fixes the problem and the back light comes back on!

[Matteo Croce (teknoraver)]

yes, power plug / unplug actually works