Hi.

I have aided a work colleague in purchasing a Lenovo G400s with i5 processor and Nvidia graphics.

I have installed Mint 14 KDE edition and all is well.... except:

When the laptop is started up the screen brightness is 0. It is black. If I press keyboard the brightness control keys to increase brightness I get a visible display. Also, once logged in the KDE settings take over and the display works 100% fine. The screen leaps into full brightness - and is really clear.

I HAVE tried the fix:

The file /etc/rc.local add before line *exit 0*:
*echo 5 > /sys/class/backlight/acpi_video0/brightness
exit 0 *
Where *5* is the brightness level from 0 to 10
In fact, you have to set your brightness as you want. Then you open the
file :
*/sys/class/backlight/acpi_video0/*actual_brightness

shown here:

https://bugs.launchpad.net/ubuntu/+s...l/+bug/1168188

It does NOT work on the Lenovo. However, using the command as root in konsole works! I assume this is a permissions problem because I cannot set this via the CLI if not logged in as root.

I have modified rc.local to no avail. I have installed xbacklight and confirmed that works... but not from rc.local on start up.

Not sure even where to go for diagnostics on this. I am still relatively new to Linux and my new job is BACK BREAKING - twelve hour days, weekends, 'holidays.' My wife is dragging me away from this machine to sleep. So time for fix hunting is limited.

Good news is that every thing else works fine and the SW is all there.

Got to eat and sleep. Thanks in advance. I am putting this in Mint because I suspect Mint is handling things a little differently to Unbuntu.

---------- Post added 08-18-13 at 04:28 PM ----------

Sorry - I am tired... It is mint *15* - not 14.

at what time the brightness is set zero? I suppose it is correct on the module loading and you can see the boot messages, but, probably, KDE or even Xserver changes it?

I also have a Lenovo laptop (Not sure the model off the top of my head) and am running Linux Mint 15.

I have tried what you mentioned, which did not work. I then installed xbacklight and stuck a command to set the brightness in /etc/rc.local, but it also does not seem to have any effect.

If I run the same command from the command line, it works, just not on startup.

Not sure what else to try...

Maybe I need to delay longer before running the command???

http://forums.linuxmint.com/viewtopi...=83538#p484265

I have not tried them yet...

Modifying grub the way suggested in the above link worked for me. I have a Lenovo G400s (Core i3 though). My linux (ubuntu/Mint 15 & 16) blanked out right from the time I selected them from BCD boot menu. Now this works perfectly.