Cannot control brightness settings on Dell XPS L502X

lghizoni · 01-02-2012, 08:02 AM

Hello all,

I just aquired a Dell XPS L502X and installed Slackware 13.37.

Till now, I cannot control the brightness. There's an applet of Brightness, but doesn't work.

I'm using Xfce interface. Could that be problem? Can someone help me?

Thank you

onebuck · 01-02-2012, 08:10 AM

Hi,

Try the 'Fn + up or down arrow' for the Dell.

willysr · 01-02-2012, 08:23 AM

check /sys/class/backlight/intel_backlight/brightness
that's what i used in my laptop (ASUS ULV 80 Series)

ceyx · 01-02-2012, 11:55 AM

I remap my keyboard to use the keys I want.

In an X terminal window, run "xev" ( you may have to install it first )
Press the keys you want to use. ( I map the unused Fn keys )
Note the keycode from the output of xev.

If you cannot see any output for a particular key, try another. Some are dead / masked out out.

Modify this code ( mine are f5 and f6 ) substituting your keycodes:

keycode 71 = XF86MonBrightnessDown NoSymbol XF86MonBrightnessDown
keycode 72 = XF86MonBrightnessUp NoSymbol XF86MonBrightnessUp

Create a file called .Xmodmap with the above code in it and drop it into your home folder. Note the dot and the captial X.

reboot and test your new keys ! This can be done with any keys - multimedia keys for example.

Take off your sunglasses and enjoy the screen ....

lghizoni · 01-03-2012, 08:16 AM

Quote:

Originally Posted by onebuck

Hi,

Try the 'Fn + up or down arrow' for the Dell.

Hello,

I've already done it. When I try that, the brightness applet appears in the screen normally, but the brightness itself doesn't change.

Thank you anyway!

lghizoni · 01-03-2012, 08:19 AM

Quote:

Originally Posted by willysr

check /sys/class/backlight/intel_backlight/brightness
that's what i used in my laptop (ASUS ULV 80 Series)

Hi,

When I getting into /sys/class/backlight/ directory and run ls, there's only acpi_video0, which is a symbolic link to ../../devices/virtual/backlight/acpi_video0.

I just don't know what to do...

Thanks friend.

onebuck · 01-03-2012, 09:08 AM

Hi,

Quote:

Originally Posted by lghizoni

Hello,

I've already done it. When I try that, the brightness applet appears in the screen normally, but the brightness itself doesn't change.

Thank you anyway!

Works for my Dell with a fresh install. It seems you are getting close.
Structure on my laptop, notice the other links;

Quote:

buck:/sys/class/backlight/acpi_video0# ls -al
total 0
drwxr-xr-x 3 root root 0 2012-01-03 08:54 ./
drwxr-xr-x 3 root root 0 2012-01-03 08:54 ../
-r--r--r-- 1 root root 4096 2012-01-03 08:55 actual_brightness
-rw-r--r-- 1 root root 4096 2012-01-03 08:55 bl_power
-rw-r--r-- 1 root root 4096 2012-01-03 08:55 brightness
lrwxrwxrwx 1 root root 0 2012-01-03 08:55 device -> ../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:1a/LNXVIDEO:00/device:1c/
-r--r--r-- 1 root root 4096 2012-01-03 08:55 max_brightness
drwxr-xr-x 2 root root 0 2012-01-03 08:55 power/
lrwxrwxrwx 1 root root 0 2012-01-03 08:55 subsystem -> ../../../../class/backlight/
-rw-r--r-- 1 root root 4096 2012-01-03 08:55 uevent

What do you see in 'brightness'? Just cat brightness, do the Fn up/Down then 'cat brightness' to see if it changes.

I am wondering what you see in '/var/log/Xorg.0.log'?

lghizoni · 01-03-2012, 12:02 PM

Quote:

Originally Posted by onebuck

Hi,
Works for my Dell with a fresh install. It seems you are getting close.
Structure on my laptop, notice the other links;
What do you see in 'brightness'? Just cat brightness, do the Fn up/Down then 'cat brightness' to see if it changes.

I am wondering what you see in '/var/log/Xorg.0.log'?

Hello

I ran ls -al, and that's the output:

bash-4.1# ls -al
total 0
drwxr-xr-x 3 root root 0 Jan 3 17:44 .
drwxr-xr-x 3 root root 0 Jan 3 17:44 ..
-r--r--r-- 1 root root 4096 Jan 3 17:45 actual_brightness
-rw-r--r-- 1 root root 4096 Jan 3 17:52 bl_power
-rw-r--r-- 1 root root 4096 Jan 3 17:52 brightness
lrwxrwxrwx 1 root root 0 Jan 3 17:44 device -> ../../../LNXSYSTM:00/device:00/PNP0A08:00/LNXVIDEO:01/device:35
-r--r--r-- 1 root root 4096 Jan 3 17:44 max_brightness
drwxr-xr-x 2 root root 0 Jan 3 17:52 power
lrwxrwxrwx 1 root root 0 Jan 3 17:44 subsystem -> ../../../../class/backlight
-rw-r--r-- 1 root root 4096 Jan 3 17:44 uevent

I ran 'cat brightness', did the Fn up/Down then 'cat brightness', but it didn't change.

About '/var/log/Xorg.0.log', it's a huge file. Should I paste it here?

jimmy_page_89 · 01-03-2012, 12:19 PM

Try to add on /etc/lilo.conf, at the line "append"

Code:

 acpi_osi=Linux

then reboot and try with the Fn buttons

lghizoni · 01-03-2012, 12:26 PM

Quote:

Originally Posted by jimmy_page_89

Try to add on /etc/lilo.conf, at the line "append"

Code:

 acpi_osi=Linux

then reboot and try with the Fn buttons

Hello,

I edited lilo.conf and inserted acpi_osi=Linux in 'append', like this:

append="quiet splash vt.default_utf8=1 nomodeset acpi_osi=Linux"

Then I ran lilo -v and rebooted, but still doesn't work.

Thanks.

onebuck · 01-03-2012, 02:48 PM

Hi,

Quote:

Originally Posted by lghizoni

Hello

I ran ls -al, and that's the output:

bash-4.1# ls -al
tomtal 0
drwxr-xr-x 3 root root 0 Jan 3 17:44 .
drwxr-xr-x 3 root root 0 Jan 3 17:44 ..
-r--r--r-- 1 root root 4096 Jan 3 17:45 actual_brightness
-rw-r--r-- 1 root root 4096 Jan 3 17:52 bl_power
-rw-r--r-- 1 root root 4096 Jan 3 17:52 brightness
lrwxrwxrwx 1 root root 0 Jan 3 17:44 device -> ../../../LNXSYSTM:00/device:00/PNP0A08:00/LNXVIDEO:01/device:35
-r--r--r-- 1 root root 4096 Jan 3 17:44 max_brightness
drwxr-xr-x 2 root root 0 Jan 3 17:52 power
lrwxrwxrwx 1 root root 0 Jan 3 17:44 subsystem -> ../../../../class/backlight
-rw-r--r-- 1 root root 4096 Jan 3 17:44 uevent

I ran 'cat brightness', did the Fn up/Down then 'cat brightness', but it didn't change.

About '/var/log/Xorg.0.log', it's a huge file. Should I paste it here?

Just look to see if the Dell is recognized for Fn & WMI Hotkeys. You should see a large section that handles this listed in the log. DO you use a '/etc/X11/xorg.conf' file or not?

Cheesesteak · 01-08-2012, 03:38 AM

I have an XPS 17 (L702X), and I ordered my laptop specifically without Optimus support.
If your laptop only has Nvidia graphics, the fix is simple.

1. Install Nvidia binary drivers
2. Edit your xorg.conf file and add this line to your Device section:

Code:

Option "RegistryDwords" "EnableBrightnessControl=1"

Example:

Code:

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    Option "NoLogo" "1"
    Option "RegistryDwords" "EnableBrightnessControl=1"
EndSection

Next time you start X, your controls should work.