[gm45] samsung x360-aa03 backlight control does not work with KMS

[Sergey]

Ubuntu 9.10 with latest updates, booted with KMS, provides /sys/devices/virtual/backlight/acpi_video0 interface, but changing
/sys/devices/virtual/backlight/acpi_video0/brightness has no effect (pressing brightness keys in Gnome says that it changes brightness, but there is no visual effect).
Booting with i915.modeset=0 and then xrandr --output LVDS --set BACKLIGHT_CONTROL legacy
allows to change display brightness, but I get blinking screen on console (Alt-Ctrl-F1)
The trick with
lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
setpci -s 00:02.0 F4.B=80
works.

> lsb_release -rd
Description: Ubuntu 9.10
Release: 9.10
> uname -a
Linux sergey-laptop 2.6.32-020632-generic #020632 SMP Thu Dec 3 10:09:58 UTC 2009 x86_64 GNU/Linux
> lspci -vvnn
...
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07)
 Subsystem: Samsung Electronics Co Ltd Device [144d:c03e]
 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
 Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0
 Interrupt: pin A routed to IRQ 29
 Region 0: Memory at fc000000 (64-bit, non-prefetchable) [size=4M]
 Region 2: Memory at d0000000 (64-bit, prefetchable) [size=256M]
 Region 4: I/O ports at 1800 [size=8]
 Capabilities: [90] Message Signalled Interrupts: Mask- 64bit- Queue=0/0 Enable+
  Address: fee0300c Data: 41a1
 Capabilities: [d0] Power Management version 3
  Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
  Status: D0 PME-Enable- DSel=0 DScale=0 PME-
 Kernel driver in use: i915
 Kernel modules: i915

[Philip Muškovac (yofel)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This bug did not have a package associated with it, which is important for ensuring that it gets looked at by the proper developers. You can learn more about finding the right package at https://wiki.ubuntu.com/Bugs/FindRightPackage. I have classified this bug as a bug in xserver-xorg-video-intel.

When reporting bugs in the future please use apport, either via the appropriate application's "Help -> Report a Problem" menu or using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Vikram Dhillon (dhillon-v10)]

This issue was reported against karmic, so can you confirm if this issue exists with the most recent Lucid Lynx 10.04 Alpha release? ISO CD images are available at http://cdimage.ubuntu.com/releases/lucid/ . Thanks in advance.

[Sergey (sergey-dodo)]

Tried Lucid, alpha-2, x86_64. No improvement. Gnome indicator shows brightness changes, but no visual effect.

I've build a kernel module, based on Greg Kroah-Hartman code
http://lists.freedesktop.org/archives/intel-gfx/2009-August/003942.html
which controls the brightness via SABI, installed it, booted kernel with acpi_backlight=vendor option, and got correct brightness control. The project at http://code.google.com/p/easy-slow-down-manager/ contains samsung-backlight module with this code.
Maybe you could consider incorporating SABI support into the kernel (or at least ubuntu kernel)? I've came across lots of messages from Samsung laptop owners with the same problem.

[Vikram Dhillon (dhillon-v10)]

Thanks for testing and reporting back. Marking this one new.

[Vikram Dhillon (dhillon-v10)]

Also it would help if you can do apport-bug 508737 so we can have get information on this bug.

[Sergey (sergey-dodo)]

Architecture: amd64
DistroRelease: Ubuntu 9.10
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
Package: xserver-xorg-video-intel 2:2.9.0-1ubuntu2.1
PackageArchitecture: amd64
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=ru_RU.UTF-8
RelatedPackageVersions:
 xserver-xorg 1:7.4+3ubuntu10
 libgl1-mesa-glx 7.6.1~git20091217.20ee2759-0ubuntu0~xup~1
 libdrm2 2.4.14-1ubuntu1
 xserver-xorg-video-intel 2:2.9.0-1ubuntu2.1
 xserver-xorg-video-ati 1:6.12.99+git20090929.7968e1fb-0ubuntu1
Uname: Linux 2.6.32-020632-generic x86_64
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
system:
 distro: Ubuntu
 architecture: x86_64kernel: 2.6.32-020632-generic

[Bryce Harrington (bryce)]

[@Vikram, after a reporter has re-tested against lucid and found the issue still valid, please set the status to Confirmed.]