Arch Linux

finarfin

Member

Registered: 2010-03-15

Posts: 24

2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

HI,

after the yesterday update of my ArchLinux, i have a problem with brightness of my monitor.

The backlight seems to doesn't work properly. More precisely, if i have the AC plugged in the backlight is off (with a low brightness), if i unplug the AC and go to battery power then the backlight turn on and i have my usual brightness.

I have an Ati Radeon graphic card.
In

/proc/acpi

There isn't any video folder
In

/sys/class/backlight

There isn't anything, the folder is empty.
The grub line is:

kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/7795b68b-9d94-4d49-8f1e-e1fa3149c886 ro radeon.modeset=1

it seems that When the message:

Waiting udev events to be processed

appears the backlight is turnde off.
Anyone can help me?

Bye,
Ivan

Last edited by finarfin (2011-04-12 20:43:36)

hongy19

Member

From: China

Registered: 2005-04-08

Posts: 85

Website

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

would you provide the kernel version, dmesg result for further analysis?

finarfin

Member

Registered: 2010-03-15

Posts: 24

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

Kernel Version:

Linux azraphel 2.6.38-ARCH #1 SMP PREEMPT Wed Mar 30 07:14:27 UTC 2011 i686 AMD Sempron(tm) SI-42 AuthenticAMD GNU/Linux

And dmesg is here: http://pastebin.com/hUphk3pX

bye,
Ivan

finarfin

Member

Registered: 2010-03-15

Posts: 24

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

Hi,

anyone please could help me?
Is very unconfortable to have this dark screen!!!!
Please

finarfin

Member

Registered: 2010-03-15

Posts: 24

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

Ok,
i've solved the problem by adding:

acpi_osi=Linux 
acpi_backlight=vendor

to /boot/grub/menu.lst

Then the kernel line in my grub configuration now is:

kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/7795b68b-9d94-4d49-8f1e-e1fa3149c886 ro radeon.modeset=1 acpi_osi=Linux acpi_backlight=vendor

Bye,
Ivan

Last edited by finarfin (2011-04-16 10:46:18)

Lord BlackFox

Member

Registered: 2010-04-23

Posts: 4

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

for me it doesn't work. Have you done something more?
And by the way, which drivers do you use?

Thanks for your help...

bloom

Member

Registered: 2010-08-18

Posts: 749

Website

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

For me it doesn't work.

For me neither.
Any hints would be appreciated.

---

gh · da · ds

Lord BlackFox

Member

Registered: 2010-04-23

Posts: 4

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

Okay, I've downgraded in 2.6.37, set backlight to maximum, and upgraded the kernel again. You have to add the text

It seems like
acpi_osi=Linux 
acpi_backlight=vendor

to the grub/menu.lst file BEFORE reboot in 2.6.38;

The older versions of the kernel are available here: http://schlunix.org/archlinux/core/os/x86_64/

bloom

Member

Registered: 2010-08-18

Posts: 749

Website

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

Okay, I've downgraded in 2.6.37, set backlight to maximum, and upgraded the kernel again.

I downgraded to 2.6.37.5-1 and my /sys/class/backlight directory is still empty.
Could you give more details ?

---

gh · da · ds

Lord BlackFox

Member

Registered: 2010-04-23

Posts: 4

Re: 2.6.38 . Ati Radeon backlight (or brightness) doesn't work properly

I don't remember where it is exactly. Look for acpi directory, or try with the find command:

find / -name backlight