PowerDevil selects the incorrect brightness interface

[Sparhawk]

I upgraded to Kubuntu 13.04, and my brightness keys will not select the correct interface. This worked fine in Kubuntu 12.10, if I put "acpi_backlight=vendor" in the grub options.

Now, when /etc/default/grub contains
    GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=vendor"
/sys/class/backlight/ contains dell_backlight and intel_backlight. Pressing the brightness keys does nothing to the display, but modifies the value in dell_backlight/brightness . However, if I manually modify the values in intel_backlight/brightness , the backlight changes as expected.

If I modify /etc/default/grub to contain
    GRUB_CMDLINE_LINUX_DEFAULT=""
/sys/class/backlight/ now contains acpi_video0 , acpi_video1 and intel_backlight . Now, the brightness keys do work (somewhat), and the value of acpi_video1/brightness is modified.

However, "acpi_backlight=vendor" gives me more control over the backlight. For example, I can reduce the backlight down to 0% and have the screen turn off. Without this grub option, when I reduce acpi_video1/brightness to 0 with the brightness keys, the backlight is still on. Hence, it seems that the brightness keys should really modify intel_backlight instead of acpi_video1.

As per [1], I'll file a bug against the kernel.
[1] http://community.kde.org/Solid/PowerDevil/Brightness

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: linux-image-3.8.0-21-generic 3.8.0-21.32
ProcVersionSignature: Ubuntu 3.8.0-21.32-generic 3.8.8
Uname: Linux 3.8.0-21-generic x86_64
ApportVersion: 2.9.2-0ubuntu8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: lee 2407 F.... pulseaudio
CRDA:
 country AU:
  (2402 - 2482 @ 40), (N/A, 20)
  (5170 - 5250 @ 40), (3, 23)
  (5250 - 5330 @ 40), (3, 23), DFS
  (5735 - 5835 @ 40), (3, 30)
Date: Sun May 19 13:59:39 2013
HibernationDevice: RESUME=UUID=a1f7da64-6043-4164-b1c4-739393bca744
InstallationDate: Installed on 2012-12-16 (153 days ago)
InstallationMedia: Kubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.1)
MachineType: Dell Inc. Dell System XPS L702X
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-21-generic root=UUID=db0afad2-4157-4cef-adb5-4da2aa4243f0 ro
RelatedPackageVersions:
 linux-restricted-modules-3.8.0-21-generic N/A
 linux-backports-modules-3.8.0-21-generic N/A
 linux-firmware 1.106
SourcePackage: linux
UpgradeStatus: Upgraded to raring on 2013-04-26 (22 days ago)
dmi.bios.date: 09/07/2012
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A19
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 0XN71K
dmi.board.vendor: Dell Inc.
dmi.board.version: FAB1
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: 0.1
dmi.modalias: dmi:bvnDellInc.:bvrA19:bd09/07/2012:svnDellInc.:pnDellSystemXPSL702X:pvr:rvnDellInc.:rn0XN71K:rvrFAB1:cvnDellInc.:ct8:cvr0.1:
dmi.product.name: Dell System XPS L702X
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.10 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.10-rc2-saucy/

[Sparhawk (sparhawkthesecond)]

I attempted installing the latest kernel (v3.10-rc3-saucy), but I ran into a bit of trouble. I got the error message as follows:

Examining /etc/kernel/header_postinst.d.
run-parts: executing /etc/kernel/header_postinst.d/dkms 3.10.0-031000rc3-generic /boot/vmlinuz-3.10.0-031000rc3-generic
Traceback (most recent call last):
  File "/usr/share/apport/package-hooks/dkms_packages.py", line 22, in <module>
    import apport
ImportError: No module named apport
Error! Bad return status for module build on kernel: 3.10.0-031000rc3-generic (x86_64)
Consult /var/lib/dkms/nvidia-304/304.88/build/make.log for more information.
Setting up linux-image-3.10.0-031000rc3-generic (3.10.0-031000rc3.201305261935) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.10.0-031000rc3-generic /boot/vmlinuz-3.10.0-031000rc3-generic
run-parts: executing /etc/kernel/postinst.d/dkms 3.10.0-031000rc3-generic /boot/vmlinuz-3.10.0-031000rc3-generic
Traceback (most recent call last):
  File "/usr/share/apport/package-hooks/dkms_packages.py", line 22, in <module>
    import apport
ImportError: No module named apport
Error! Bad return status for module build on kernel: 3.10.0-031000rc3-generic (x86_64)
Consult /var/lib/dkms/nvidia-304/304.88/build/make.log for more information.

As per the linked page, I understand that this might be from conflicts with the nvidia driver. Should I uninstall these as recommended, and proceed? I didn't try this immediately, since I couldn't work out how I would reinstall them after testing.

[Sparhawk (sparhawkthesecond)]

Possibly related: https://bugs.kde.org/show_bug.cgi?id=296403