Originally Posted by Zem
Here it is:
/sys/module/nvidiabl/parameters$ cat *
Ok, I have no clue with this, the wole register is screwed up. We will try to log writes and reads of the register. This is a bit dangerous, so do it only if you're a bit familiar with Linux command line.
sudo nano /etc/rc2.d/S00mmiotrace
echo mmiotrace > /sys/kernel/debug/tracing/current_tracer
echo Starting > /sys/kernel/debug/tracing/trace_marker
modprobe -r nvidia
modprobe -r nvidiabl
echo Inserting nvidia > /sys/kernel/debug/tracing/trace_marker
echo Inserting nvidiabl > /sys/kernel/debug/tracing/trace_marker
sudo chmod +x /etc/rc2.d/S00mmiotrace
After reboot, Ubuntu may complain that the graphic driver didn't initialize properly. Ask to try again. If you're stuck, do CTRL+ALT+F2, login, type "sudo rm /etc/rc2.d/S00mmiotrace" then "sudo reboot". If your desktop environment boots up fine:
cat /sys/kernel/debug/tracing/trace_pipe > ~/mydump.txt &
sudo su -c "echo playing with the backlight > /sys/kernel/debug/tracing/trace_marker"
Keep the terminal window open and change you backlight brightness up and down a bit. After that:
sudo su -c "echo break backlight register > /sys/kernel/debug/tracing/trace_marker"
And play a movie fullscreen until you reproduce your problem. Then:
sudo su -c "echo nop > /sys/kernel/debug/tracing/current_tracer"
sudo rm /etc/rc2.d/S00mmiotrace
Reboot and publish here the content of the file mydump.txt from your home directory. If the file is big, keep only the end starting with the text string "playing with the backlight".