Arch Linux

ilikepie

Member

Registered: 2009-10-28

Posts: 38

Samsung laptop flickers when trying to adjust backlight brightness

Up until two months ago, whenever I wanted to adjust the brightness on my Samsung laptop with the fn keys, the screen would flicker and just reset to the blinding, highest level of brightness. To get anything done I had to manually edit some file in /sys/class/backlight/acpi_whatever.

Then I found I could add this to my kernel boot line and presto, brightness adjustment worked:

acpi_backlight=vendor

But today I did a full system upgrade and it's back to the frustrating erratic behavior, even though the kernel line is there. I've also tried adding 'acpi_osi=Linux' to the kernel line to no avail.  What am I missing?

lsmod does mention the 'samsung_laptop' module is loaded, which I believe is the one that's supposed to be used for adjusting brightness.

Last edited by ilikepie (2012-06-15 20:10:32)

ilikepie

Member

Registered: 2009-10-28

Posts: 38

Re: Samsung laptop flickers when trying to adjust backlight brightness

Update - In /sys/class/backlight, I have intel_backlight and samsung.

Echoing values to  /sys/class/backlight/samsung/brightness yields erratic behavior, while doing the same to /sys/class/backlight/intel_backlight/brightness works perfectly. So how could I specify intel_backlight as a default for X to use?

archel

Member

Registered: 2011-11-04

Posts: 46

Re: Samsung laptop flickers when trying to adjust backlight brightness

Which DE do you use?

What's your Samsung model?

I have similar problem with samsung_laptop module.

ilikepie

Member

Registered: 2009-10-28

Posts: 38

Re: Samsung laptop flickers when trying to adjust backlight brightness

Hi, I have an NP300-E5A ("Series 3") and I use XFCE.

NekySerbia

Member

Registered: 2008-01-12

Posts: 40

Re: Samsung laptop flickers when trying to adjust backlight brightness

I have the exactly same problem as you, model NP300-V5Z.

:EDIT:

Yet again, same solution to the same problem: https://bbs.archlinux.org/viewtopic.php … 4#p1068094

I could swear that this approach wasn't working for some time...maybe the samsung-tools upgrade from today resolved some issues, who knows.

Last edited by NekySerbia (2012-08-14 22:47:47)