Brightness control not working on Vaio TT with 2.6.31 rc6 kernel

[Joan Tur]

Binary package hint: linux-image-2.6.31-6-generic

Hi.

I'm using Karmic alpha3 64 bits on my Sony Vaio TT11LN/B; in both linux-image-2.6.31-5-generic and linux-image-2.6.31-6-generic, the brightness control keys don't work out of the box (Fn +F5/F6), and the screen is not getting dimmed when on battery, as stated in the power manager.

These keys don't generate events either (tested using "xbindkeys -k").

/sys/class/backlight/ is empty.

**Important** in 9.04 those function keys did not work, but Gnome was dimming the lcd power when on battery. Also, when running the kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.31-rc6/ brightness works out of the box, and so do those function keys.

root@quinitt:/# lsb_release -rd
Description: Ubuntu karmic (development branch)
Release: 9.10

root@quinitt:/# apt-cache policy linux-image-2.6.31-6-generic
linux-image-2.6.31-6-generic:
  Instal·lat: 2.6.31-6.25
  Candidat: 2.6.31-6.25
  Taula de versió:
 *** 2.6.31-6.25 0
        500 http://archive.ubuntu.com karmic/main Packages
        100 /var/lib/dpkg/status

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-7-generic

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-8-generic 2.6.31-8.28

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-9-generic 2.6.31-9-29

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-10-generic 2.6.31-10.30

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-10-generic 2.6.31-10.32 (AFAIK based on final 2.6.31)

[Eric Donkersloot (ericd)]

Could this be related to: https://bugzilla.redhat.com/show_bug.cgi?id=519105 ?

[Joan Tur (joantur)]

Yes, it seems to be the same problem, despite it appears on different kernel versions in Ubuntu:

Lcd brightness control works with:
-Jaunty's linux-image (the Fn keys don't work, but Gnome can control the brightness)
-Karmic's linux-image-2.6.30 (before changing to 2.6.31),
-http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.30.5/ (the one I'm now using)

And it does NOT work with:
-Karmic's linux-image-2.6-31-5 to -10, as mentioned above
-http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.31/

So in Ubuntu there seems to be a regression in kernel 2.6.31.

Note: I also get the same message when removing and inserting sony_laptop module:
"sony-laptop: brightness ignored, must be controlled by ACPI video driver"

[Joan Tur (joantur)]

Same behaviour with Karmic's linux-image-2.6.31-11-generic 2.6.31-11.36

Note: with kernel http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.30.6/ brightness works fine also

[Joan Tur (joantur)]

It finally works fine with Karmic's linux-image-2.6.31-11-generic 2.6.31-11.38 !!

Thanks! ;)

[Eric Donkersloot (ericd)]

Is is possible to find out what patch made it into this kernel that made it work again ?

[Joan Tur (joantur)]

I'm sure some of the people who's being notified of this bug may answer this question. I'm sorry i can't.

[Eric Donkersloot (ericd)]

See the kernel changelog here: http://changelogs.ubuntu.com/changelogs/pool/main/l/linux/linux_2.6.31-11.38/changelog

[Joan Tur (joantur)]

"sony" & "bright" don't appear in that changelog, so I assume one the few lines containing "acpi" has done the trick...

"sony-laptop: brightness ignored, must be controlled by ACPI video driver"

Regards,

[Eric Donkersloot (ericd)]

Duplicate of #428910