# Can't change brightness in Xorg but can in tty thinkpad T400

## stupidkid

Hello, I somehow can't change brightness in xorg but can in the terminals while using the discrete graphics. The card is 

01:00.0 VGA compatible controller: ATI Technologies Inc Mobilitiy Radeon HD 3400 Series

I'm using the radeonhd driver for X. To change brightness in X I would have to do a ctrl-atl-f1 and change brightness there then switch back to X.

Can someone help me fix this?

Thanks.

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## pappy_mcfae

Yes. Take a look at the display properties as I've set them up in my kernel seeds. The settings you see allow you to use ACPI with the video display, which should give you that ability. You need to change the display settings, then the ACPI video option will come up, and you can select it. 

If you prefer, send your kernel .config along with the results of lspci -n and cat /proc/cpuinfo as well as your /etc/fstab file, and I'll set you up with a kernel that should support dimming under X.

Blessed be!

Pappy

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## Khumarahn

Great feature I didn't know - acpi for video, thanks )

I had a situation just like stupidkid described.

And I recompiled my kernel with acpi video control, and now when I try to change brightness, gnome animates a nice icon for brightness, and it changes - but only on icon.

Real brightness does not change - regardless of ambient light sensor is on or off.

Though, I have an ambient light sensor, and laptop is HP 8710p.

What could it be?   :Shocked: 

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## d2_racing

You will need at least in the kernel :

```

CONFIG_ACPI_VIDEO=m

CONFIG_VIDEO_OUTPUT_CONTROL=m

```

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## Khumarahn

```

CONFIG_ACPI_VIDEO=m

CONFIG_VIDEO_OUTPUT_CONTROL=m

```

I have it. May be, I should configure or recompile hal or xorg?

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## pappy_mcfae

No, those things should be compiled in. Look at one of my kernel seeds for reference.

Blessed be!

Pappy

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## Khumarahn

 *pappy_mcfae wrote:*   

> compiled in

 

Oh, I didn't notice 'm' there. Of course, they are compiled in. Yesterday I adopted one of your seeds, and even rebuilt all the system, but still I can change brightness in tty, but can't in gnome.

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## pappy_mcfae

Do you have acpi and acpid emerged? If not, do so. Other than that, you may have to do some searching. Brightness works for my laptop without anything extra having to be done over what I've told you. There may be a different sort of magick required to get yours working. I'm sure someone here has done so, and will pop along eventually. That's the beauty of Gentoo's forums.

Blessed be!

Pappy

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## Khumarahn

Hm... acpi is masked. Do you truly believe, I should unmask it and emerge?

acpid is running, and lots of things work correctly, and when I change brightness in tty-12, I see messages like 

```

Apr 21 17:14:56 localhost acpid: received event "video C162 00000086 00000000"

Apr 21 17:14:56 localhost acpid: notifying client 4703[102:1002]

Apr 21 17:14:56 localhost acpid: executing action "/etc/acpi/default.sh video C162 00000086 00000000"

Apr 21 17:14:56 localhost logger: ACPI event unhandled: video C162 00000086 00000000

Apr 21 17:14:56 localhost acpid: action exited with status 0

Apr 21 17:14:56 localhost acpid: completed event "video C162 00000086 00000000"

```

Actually, control of brightness for hp 8710p is almost never needed as is has ambient light sensor that works pretty well, so that I even didn't notice that brightness doesn't change in X for moer than 2 months of running gentoo. So I doubt that anybody was really interested in this  :Wink:   And I'm just curious, because I like the system and how it works.

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## pappy_mcfae

If I ask someone to install a program, I mean it. However, if things are working, then do as you will. As for the light sensor, I have no idea.

Blessed be!

Pappy

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## Khumarahn

 *pappy_mcfae wrote:*   

> If I ask someone to install a program, I mean it. However, if things are working, then do as you will. As for the light sensor, I have no idea.

 

I just have no idea what it could change.

Anyway, I unmasked and compiled acpi, and rebooted computer. Nothing changed (

Though, I've found the bug someone summitted to https://bugs.launchpad.net/bugs/308784 - just the same in Ubuntu. So you were right - I am not lonely here )

People say, it could be bug in nvidia-drivers.

By the way, stupidkid, do you have nvidia card, and use nvidia-drivers for X?

If I run 

```
eselect opengl set xorg-x11
```

, will I use xorg drivers for X, so that I will be able to test that? (will I have to reboot, or it will be enough to restart X?)

Pappy, thank you for your help, I appreciate and value it.

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## pappy_mcfae

You're most welcome!

Blessed be!

Pappy

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