8086:0046 [Dell XPS 15 L501x] Unable to change backlight by default

[Benjamin Hilton]

While I disabled my nvidia card in BIOS, I am unable to change the backlight by default.

WORKAROUND: Use both kernel parameters:
acpi_backlight=vendor dell_laptop.backlight=0

Having just 'acpi_backlight=vendor' means that if I quickly and repeatedly press the key to change brightness, it eventually lowers, but sometimes the down key makes it higher and visa versa, making it difficult to change. Adding 'dell_laptop.backlight=0' makes the controls work perfectly normally. But when I boot, I get the message: dell_laptop: '0' invalid parameter for 'backlight', at which my computer then continues to boot and works normally, with the brightness control working.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: linux-image-3.8.0-22-generic 3.8.0-22.33
ProcVersionSignature: Ubuntu 3.8.0-22.33-generic 3.8.11
Uname: Linux 3.8.0-22-generic x86_64
ApportVersion: 2.9.2-0ubuntu8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: benjamin 4172 F.... pulseaudio
 /dev/snd/controlC0: benjamin 4172 F.... pulseaudio
Date: Thu May 30 19:07:26 2013
HibernationDevice: RESUME=UUID=74004122-cb29-4972-92c0-8bd036223958
InstallationDate: Installed on 2013-04-26 (34 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MachineType: Dell Inc. XPS L501X
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-22-generic root=UUID=df9e5312-fd68-4a0f-99fb-8b6667021bea ro quiet splash acpi_backlight=vendor dell_laptop.backlight=0
RelatedPackageVersions:
 linux-restricted-modules-3.8.0-22-generic N/A
 linux-backports-modules-3.8.0-22-generic N/A
 linux-firmware 1.106
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/15/2010
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A03
dmi.board.name: 00CKNG
dmi.board.vendor: Dell Inc.
dmi.board.version: A03
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A03
dmi.modalias: dmi:bvnDellInc.:bvrA03:bd10/15/2010:svnDellInc.:pnXPSL501X:pvrA03:rvnDellInc.:rn00CKNG:rvrA03:cvnDellInc.:ct8:cvrA03:
dmi.product.name: XPS L501X
dmi.product.version: A03
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-rc4-saucy/

[Benjamin Hilton (barhilton)]

Still get the error message with the latest kernel - but I did get the following error message whilst installing so it may not have worked correctly:
ImportError: No module named apport
Error! Bad return status for module build on kernel: 3.10.0-031000rc4-generic (x86_64)
Consult /var/lib/dkms/nvidia-304/304.88/build/make.log for more information.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.10.0-031000rc4-generic /boot/vmlinuz-3.10.0-031000rc4-generic
update-initramfs: Generating /boot/initrd.img-3.10.0-031000rc4-generic
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168g-3.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8106e-2.fw for module r8169

[Joseph Salisbury (jsalisbury)]

This issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report[0]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug.

Please follow the instructions on the wiki page[0]. The first step is to email the appropriate mailing list. If no response is received, then a bug may be opened on bugzilla.kernel.org.

Once this bug is reported upstream, please add the tag: 'kernel-bug-reported-upstream'.

[0] https://wiki.ubuntu.com/Bugs/Upstream/kernel

[Benjamin Hilton (barhilton)]

For which driver should I report this bug?

[Benjamin Hilton (barhilton)]

Updating my BIOS did not change anything.

I have upgraded to 13.10, and now I no longer get the error message. Instead, dell_laptop.backlight=0 does not change anything, and I am left having to repeatedly fiddle with the keys or use "echo [brightness value] | sudo tee /sys/class/backlight/intel_backlight/brightness" to change the brightness.

Output of sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date:
A08
07/26/2011

[penalvch (penalvch)]

Benjamin Hilton, could you please test the latest mainline kernel via http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-trusty/ and advise to the results?

[David Chen (david.chen)]

I am having the similar issue on Ubuntu 13.10. Under /sys/class/backlight, I have 2 interfaces: intel_backlight and dell_backlight. By echo brightness values into 2 different interfaces, the intel one is the actual brightness control interface. Tried to remove dell-laptop kernel module, and adding acpi_backlight=vendor kernel option, brightness hotkey starts working.

[David Chen (david.chen)]

Maybe this is the fix: http://comments.gmane.org/gmane.linux.kernel/1604523

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

[Ellis Michael (emichael)]

I'm experiencing the same behavior as above. I'm using Ubuntu 13.10 and the 3.13 mainline kernel.

I was able to find a workaround that let me control the backlight brightness through the applet.

Create /etc/X11/xorg.conf.d/20-intel.conf with the following:

Section "Device"
        Identifier "HD 4000"
        Driver "Intel"
        Option "Backlight" "intel_backlight"
EndSection

However, the brightness keys are still broken. I am able to change the brightness with them, but it will only go down to about 90%. I suspect this has something to do with the dell_backlight having max_brightness 15 and the intel_backlight having max_brightness ~4600.

[penalvch (penalvch)]

Ellis Michael, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report by executing the following in a terminal:
ubuntu-bug xorg

Please ensure you have xdiagnose installed, and that you click the Yes button for attaching additional debugging information.

For more on this, please see the official Ubuntu documentation:
Ubuntu X.Org Team, Ubuntu Bug Control, and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Please note, not filing a new report will delay your problem being addressed as quickly as possible.

Thank you for your understanding.

[Jose Gómez (adler-dreamcoder)]

Backlight buttons are working fine here (XPS 15 9530, Ubuntu 14.04, kernel 3.13.2-031302-generic).

No acpi keywords added to the grub parameters, and no modification performed in any xorg.conf files.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]