Comment 0 for bug 1138168

Laptop: ASUS A54C-NB91 with BIOS version 210

Summary:
After the 3.6 kernel controlling the backlight via software (like xbacklight and the brightness applet) no longer works as intended (attempting to get brightness alters the brightness)
This was not a Issue on the older BIOS version (207), but downgrading that is not possible, and ASUS will not fix it stating the typical we don't support linux on this model
On the 3.6 kernel with the latest BIOS the backlight can't be controlled via the fn+brightness keys, that still works on the 3.7 kernel and up
i have never had the fn+brightness keys ever update /sys/class/backlight/acpi_video0/brightness under any tested scenario

The PDF file in the attachment was written a week or so ago using 12.10 with raring's kernels, however it still applies in 13.04 (fresh install using the march 1st daily iso)

I have tested Kernel versions 3.8.1-030801, 3.8.0-8, 3.7.10-030710, and 3.6.11-030611 today on raring (without using acpi_backlight=vendor)
and had the exact same results as when i did the test earlier in raring and quantal (see PDF file in attachment)

The attachment contains the following files (all system generated files are from this install)
Detailed test.pdf
dmesg_3.6.11-030611-generic
dmesg_3.7.10-030710-generic
dmesg_3.8.0-8-generic
dmesg_3.8.1-030801-generic
lspci_very_verbose
syslog

If any addition information is needed, just ask and specify the test case (12.10/13.04, with/without acpi_backlight=vendor, and kernel version)

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: linux-image-3.8.0-8-generic 3.8.0-8.17
ProcVersionSignature: Ubuntu 3.8.0-8.17-generic 3.8.0
Uname: Linux 3.8.0-8-generic x86_64
ApportVersion: 2.9-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: chad 1708 F.... xfce4-volumed
                      chad 1722 F.... pulseaudio
 /dev/snd/pcmC0D0p: chad 1722 F...m pulseaudio
CurrentDmesg:

Date: Fri Mar 1 11:31:52 2013
HibernationDevice: RESUME=UUID=a974f07b-dcae-4886-8ddb-e5a48219f891
InstallationDate: Installed on 2013-03-01 (0 days ago)
InstallationMedia: Xubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130301)
MachineType: ASUSTeK Computer Inc. K54C
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-8-generic root=UUID=5c6a915b-d2e5-4746-9c09-657e51145ad6 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.8.0-8-generic N/A
 linux-backports-modules-3.8.0-8-generic N/A
 linux-firmware 1.103
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/23/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: K54C.210
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: K54C
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrK54C.210:bd10/23/2012:svnASUSTeKComputerInc.:pnK54C:pvr1.0:rvnASUSTeKComputerInc.:rnK54C:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: K54C
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.