Comment 8 for bug 1130938

Revision history for this message
Christoph Mende (cmende) wrote :

I encountered the same problem (at least it's the same symptoms). This seems to be a bug with the backlight (possibly http://<email address hidden>/msg18396.html, n
ot sure how nouveau is related - I got hit by this on an Intel HD4000).
Luckily, I've found a quick workaround for this. Run this as root (sudo -s):
cat << EOF >> /etc/pm/sleep.d/60intel
#!/bin/sh
# Force backlight on after resume

case "$1" in
        thaw|resume)
                cd /sys/class/backlight/intel_backlight
                cat max_brightness >brightness
                ;;
        *)
                exit $NA
                ;;
esac
EOF
chmod +x /etc/pm/sleep.d/60intel

That's it. This tells the system to set the backlight to full on resume. Even if it is already set to full, this causes the video driver to re-enable the backlight. Instead of max_brightness, one could also use actual_brightness to reset to the old value.
Of course the cd line would need to be changed according to the backlight driver (whatever's there in /sys/class/backlight), like I said, this version works on an Intel HD4000, it needs modification on non-Intel obviously.