Missing Backlight Control (Samsung Laptop)

[sloothword]

Hi,

I installed Mageia 1 on my Samsung R560 Laptop.
And im amazed that some of the Lapop specific Fn-Keys work: Volume Control, Disabling Touchpad, Disabling Wifi, Num-Keys.

But sadly not the backlight control.

I can increase and decrease the value (a display showing the brightness level opens) by pressing either the fn-keys or adjusting it in power management. But the actual LCD brightness doesn't change.

I tried some tips found by googling:

Manually set brightness: echo 7 > /proc/acpi/video/ATIM/LCD/brightness

Code: Select all

# cd /proc/acpi
# ls
button/  event  fixed_events  wakeup

Add kernel module: samsung-laptop or samsung-backlight

Code: Select all

# modprobe samsung-laptop -v
insmod /lib/modules/2.6.38.7-desktop586-1.mga/kernel/drivers/platform/x86/samsung-laptop.ko.gz
FATAL: Error inserting samsung_laptop (/lib/modules/2.6.38.7-desktop586-1.mga/kernel/drivers/platform/x86/samsung-laptop.ko.gz): No such device
# dmesg
#


Thanks in advance for your help!

[wobo]

Same problem here with a Samsung R530.
Changing brightness worked with Mandriva 2010.2 and works with Mandriva 2011.0 Beta3, not with Mageia 1.

[doktor5000]

I think one of the few people with definitive information about this would be Thomas Backlund (tmb) our friendly neighborhood kernel maintainer

[isadora]

Not this is going to help you guys, but at least it's some nice piece of reading from Matthew Garrett in Livejournal.
My Acer Aspire 7720G doesn't have problems changing brightness.
This can also and easily being checked simply by:

When full brightness:
[isadora@localhost ~]$ cat /sys/devices/virtual/backlight/acpi_video0/actual_brightness
9

and when lowering brightness one step.......
[isadora@localhost ~]$ cat /sys/devices/virtual/backlight/acpi_video0/actual_brightness
7

[doktor5000]

Most of the Samsung Netbooks and Laptops need more than one Kernel patch and a really recent version of the relevant drivers.

A short comparation of Mandriva Kernel 2.6.38.7:
http://svn.mandriva.com/cgi-bin/viewvc. ... S/patches/
and Mageia 1 kernel 2.6.38.7:
http://svnweb.mageia.org/packages/cauld ... S/patches/

shows that all of the platform-x86-samsung-patches are not as patches in Mageia 1 kernel.
But like i said, the only one who should definitely know is Thomas Backlund.
So better open up a bug report ...

[isadora]

You're quite right doktor5000.

And it is right now i see, i have forgotten to bring in the link to the piece of reading at Livejournal.
There you go:
http://mjg59.livejournal.com/127103.html

[wobo]

Ok, so it's Bugzilla time - will file a report tomorrow.

[thcourbon]

Hi there,
Upping the thread a little here.
I wasn't able to find any related bug report on the mageia bugzilla except one (https://bugs.mageia.org/show_bug.cgi?id=1829) that did receive much attention.

I took the liberty to create a new one for cauldron and kernel 3.0 (https://bugs.mageia.org/show_bug.cgi?id=2175). I did so since the samsung-laptop driver was merged in 2.6.39 and I expected my netbook function keys to work (something they refuse to do...).

Does anyone made some progress on that ?

[Cornelus]

I remember that I had this problem in Mandriva 2010.2. I solved it by installing prioprietary nvidia drivers and editing /etc/X11/xorg.conf file. Try to add the following entry to Section "Device":

Option "RegistryDwords" "EnableBrightnessControl=1"

To be sure I recommend to add your user to "video" group.