[SOLVED] Laptop backlight control

Message

RMX · Post by **RMX** » Mon May 12, 2008 10:10 pm

Hello,
I can't find how to adjust my HP Pavilion DV6610EN backlight. I have read many HOWTOs and forum post but I still can't get it to work. I have /sys/class/backlight directory, but it's empty. I have included these options to my kernel:

Code: Select all

CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_LCD_CLASS_DEVICE=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y
CONFIG_BACKLIGHT_CORGI=y
CONFIG_BACKLIGHT_PROGEAR=y

Also, I don't have /proc/acpi/video directory. Can anyone help me? I want to adjust brightness for battery economics.
By the way, I noticed that screen is brighter when I unplug the power cable. This is strange, I think it should be otherway.

Cheesebaron · Post by **Cheesebaron** » Tue May 13, 2008 8:27 am

Try enabling

CONFIG_BACKLIGHT_LCD_SUPPORT
CONFIG_BACKLIGHT_CLASS_DEVICE

EDIT: Oh wait you did.

EDIT EDIT: This might be a stupid question. But do you even have acpid installed?

RMX · Post by **RMX** » Tue May 13, 2008 1:07 pm

Yes, I have acpid and it's running. I can see battery's status and so on. When I close the lid, backlight automatically turns off.

danvari · Post by **danvari** » Tue May 13, 2008 1:42 pm

did you activate acpi-video support into the kernel? your directory is empty so it might not be activated in the kernel. you will need that to control the backlight. if you cannot activate acpi-video (maybe it is not listed in the acpi section), then you have to activate some lcd brightness stuff in the kernel.

Wojtek_ · Post by **Wojtek_** » Tue May 13, 2008 2:02 pm

I have exactly the same problem. I tried booting Ubuntu Hardy LiveCD and I can adjust the brightness easily using Fn keys and/or the gnome brightness applet. Can it be caused that the liveCD uses open xorg-ati-driver whereas I have fglrx on my Gentoo installation?
Cheers,

Wojtek

RMX · Post by **RMX** » Tue May 13, 2008 2:20 pm

danvari wrote:did you activate acpi-video support into the kernel? your directory is empty so it might not be activated in the kernel. you will need that to control the backlight. if you cannot activate acpi-video (maybe it is not listed in the acpi section), then you have to activate some lcd brightness stuff in the kernel.

Well I can't find that in kernel's menuconfig. When I press / and type acpi_video, I see:

Symbol: ACPI_VIDEO [=n]
│ Prompt: Video
│ Defined at drivers/acpi/Kconfig:137
│ Depends on: !X86_VOYAGER && ACPI && X86 && BACKLIGHT_CLASS_DEVICE &&
│ Location:
│ -> Power management options
│ -> ACPI (Advanced Configuration and Power Interface) Support (ACP

But I can't find it in the menu. Maybe because it says Depends on: !X86_VOYAGER && ACPI && X86 && BACKLIGHT_CLASS_DEVICE && and my processor is x86_64?

Wojtek_ · Post by **Wojtek_** » Tue May 13, 2008 6:06 pm

I managed to get brightness working by selecting VIDEO_OUTPUT_CONTROL && INPUT (ACPI_VIDEO showed up after selecting them). After rebooting the kernel I can regulate screen brightness using Fn keys and brightness panel (which never worked before). Thanks for help.
Cheers,

Wojtek

RMX · Post by **RMX** » Tue May 13, 2008 7:17 pm

Oh, I had to select VIDEO_OUTPUT_CONTROL, everything works now.
Thank you.

Wojtek_ · Post by **Wojtek_** » Tue May 13, 2008 7:30 pm

Please add [SOLVED] to the topic then.
Cheers,

Wojtek

RMX · Post by **RMX** » Wed May 14, 2008 8:28 am

Oh, sorry, I forgot that