# Brightness controls for laptop

## avieth

When I start my system, the brightness control keys (Fn+Up, Fn+Down) work. As X starts up, they continue to work, and as far as I can tell, they function until I switch the VT. After that, I have to use a program like KDE's power manager, or 'echo x > /proc/acpi/video/GFX0/DD03/brightness' to change the brightness. Any ideas on how I can stop this annoyance and make my brightness keys work all the time?

I have this graphics controller:

```

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)                                                                                          

00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
```

Here is the ACPI section of my kernel:

```

CONFIG_ACPI=y

CONFIG_ACPI_SLEEP=y

CONFIG_ACPI_PROCFS=y

CONFIG_ACPI_PROCFS_POWER=y

CONFIG_ACPI_SYSFS_POWER=y

CONFIG_ACPI_PROC_EVENT=y

CONFIG_ACPI_AC=y

CONFIG_ACPI_BATTERY=y

CONFIG_ACPI_BUTTON=y

CONFIG_ACPI_VIDEO=y

CONFIG_ACPI_DOCK=y

CONFIG_ACPI_PROCESSOR=y

CONFIG_ACPI_HOTPLUG_CPU=y

CONFIG_ACPI_THERMAL=y

CONFIG_ACPI_BLACKLIST_YEAR=0

CONFIG_ACPI_CONTAINER=y

CONFIG_X86_ACPI_CPUFREQ=y

CONFIG_PNPACPI=y

CONFIG_BLK_DEV_IDEACPI=y

CONFIG_ATA_ACPI=y

```

Thanks.

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## gigel

maybe it's a buggy kernel driver . for instance, with kernels 2.6.30 I could've changed the brightness with kpowersave but not with the fn-whatever combination. 

fortunately asus laptop extras hade recently changed within the kernel, and now I can use both methods

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## avieth

Interesting, I do recall not having this problem with some earlier kernel. 2.6.28 I believe. Hopefully it returns to working order by the next kernel release. 

Which driver is in question here? ACPI_VIDEO?

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## gigel

 *avieth wrote:*   

> Interesting, I do recall not having this problem with some earlier kernel. 2.6.28 I believe. Hopefully it returns to working order by the next kernel release. 
> 
> Which driver is in question here? ACPI_VIDEO?

 

maybe, I don't know which one exactly, but I doubt it is ACPI_VIDEO

for instance, on my laptop, in order to be able to use the fn + F? keys I had to compile asus/medion laptop extras, which is now deprecated in favor of the new driver - asus laptop extras (i'm using 2.6.32-rc5)

the funny thing is that now i'm able to use the brightness from the fn buttons(aswell as kpowersave) + the mute/increase-decrease volume, but the wireless button doesn't work anymore (with previous driver it did - but I dont care, as I always use wireless and I don't see any reason for an extra button)

and I don't think they've made changes in the ACPI_VIDEO driver.

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## avieth

I upgraded to 2.6.31-r6, and now I cannot even change the brightness at all, not with the keys or with software. I'm going to try the latest git-sources.

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## gigel

try with the development vanilla sources - 2.6.32-rc7  :Smile: 

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## Odysseus

 *avieth wrote:*   

> When I start my system, the brightness control keys (Fn+Up, Fn+Down) work. As X starts up, they continue to work, and as far as I can tell, they function until I switch the VT. After that, I have to use a program like KDE's power manager, or 'echo x > /proc/acpi/video/GFX0/DD03/brightness' to change the brightness. Any ideas on how I can stop this annoyance and make my brightness keys work all the time?
> 
> I have this graphics controller:
> 
> ```
> ...

 

It doesn't sound like a kernel issue to me (at least with the versions prior to 2.6.31), because it works until X takes over and you switch to the VT and because it also works when you manually issue the command to adjust brightness. This indicates to me that the problem may reside with HAL and properly recognizing the "hot keys" that control your backlight. But to be on the safe side, do you have a recent version of libsmbios (newer than 0.12.1) installed? Did you build in your kernel the dcdbas module? I believe it needs to be a module. I know both of these are required for Dell backlight control to work correctly with HAL. Your manufacturer may require different modules for correct operation (visit their website for more info).

What make laptop are you using and are you running X from unstable or stable arch? I have a Dell Inspiron 9300 which fortunately has all of it's keyboard keys properly configured including the "Fn" key combos. Dell is thoroughly supported do to the cooperation between it, Ubuntu, Redhat, and Xorg. I believe that resolving our problem may be as simple as creating a .fdi file that properly instructs HAL about your keyboard's layout.

The first thing to do is to go to your laptop manufacturer's site to see if they have any recent support updates for X. If not, then the procedure would be to look at the .fdi files which reside in "/usr/share/hal/fdi". In the "information/10freedesktop" and "policy/10osvendor" directories you'll find a number of .fdi files some of which control keyboard and backlight operation (among other things). Read through them and see if you find something there which relates to your setup. Once you do, then create your own .fdi file and place it in "/etc/hal/fdi/policy" (do not place it in "/usr/share/hal/fdi" as this will get overwritten the next time HAL is rebuilt). Remember these are XML files so formatting is important. Once you log out of X and restart the X server the .fdi will become active. Hopefully this will resolve the issue.

I hope this helps,

Ciao

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