8086:0166 [Dell Inspiron 15R 5521] Impossible to adjust the screen backlight

[Alex Barattini]

the change in the level of illumination of the screen, through the corresponding option in the control panel, has no effect.

Upstream post: http://www.spinics.net/lists/linux-acpi/msg48075.html

WORKAROUND: In Ubuntu kernel only, version 3.11.0-14-generic tested:
acpi_backlight=vendor

WORKAROUND: In mainline only:
video.use_native_backlight=1

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: linux-image-3.11.0-14-generic 3.11.0-14.21
ProcVersionSignature: Ubuntu 3.11.0-14.21-generic 3.11.7
Uname: Linux 3.11.0-14-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: alex 1443 F.... pulseaudio
                      alex 11159 F.... pulseaudio
Date: Tue Dec 17 18:50:13 2013
HibernationDevice: RESUME=UUID=04335018-6e1d-453d-a8ba-25ae1c34f2eb
InstallationDate: Installed on 2013-12-14 (2 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: Dell Inc. Inspiron 5521
MarkForUpload: True
ProcEnviron:
 LANGUAGE=it
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-14-generic.efi.signed root=UUID=d4cdcfba-0a53-41d0-a9ce-0516d3fab0f0 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.11.0-14-generic N/A
 linux-backports-modules-3.11.0-14-generic N/A
 linux-firmware 1.116
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/22/2013
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A06
dmi.board.name: 0K08H3
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A06
dmi.modalias: dmi:bvnDellInc.:bvrA06:bd02/22/2013:svnDellInc.:pnInspiron5521:pvrA06:rvnDellInc.:rn0K08H3:rvrA00:cvnDellInc.:ct8:cvrA06:
dmi.product.name: Inspiron 5521
dmi.product.version: A06
dmi.sys.vendor: Dell Inc.

[Alex Barattini (alex.barattini)]

alex@alex-Inspiron-5521:~$ sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
[sudo] password for alex:
A12
10/25/2013

I updated the BIOS to version suggested but did not produce any change. It remains impossible to adjust the screen brightness

[penalvch (penalvch)]

Alex Barattini, thank you for updating your BIOS. Could you please test the latest upstream kernel available (v3.13-rc3, as rc4 doesn't have all the files yet) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.13-rc3

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

[Alex Barattini (alex.barattini)]

I tested from live-usb the daily .iso of Ubuntu. The problem persist. I attach the report generated by the command apport-cli - save bug.log linux.
Now I go to try the live-usb .iso version 12.04.03

[penalvch (penalvch)]

Alex Barattini, the latest mainline kernel is http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.13-rc3-trusty/ . Could you please test this and report the results?

[Alex Barattini (alex.barattini)]

Sorry but i'm not an expert user.
which of these .deb should I download and install?

[penalvch (penalvch)]

Alex Barattini, please see https://wiki.ubuntu.com/Kernel/MainlineBuilds .

[Alex Barattini (alex.barattini)]

ok, bug confirmed on last upstream kernel.

[penalvch (penalvch)]

Alex Barattini, thank you for performing the requested test. Would either of the following kernel parameters used separately provide a WORKAROUND:
acpi_backlight=vendor
video.use_bios_initial_backlight=0

or the following in combination:
thinkpad-acpi.brightness_enable=1 acpi_backlight=vendor

[Alex Barattini (alex.barattini)]

with the following workaround the problem is solved acpi_backlight=vendor

[penalvch (penalvch)]

Alex Barattini, thank you for performing the requested tests. Hence, this is an upstream bug. Could you please report this through the appropriate channel (would start with linux-acpi) by following the instructions _verbatim_ via https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Overview_on_Reporting_Bugs_Upstream ?

Thank you for your understanding.

[Alex Barattini (alex.barattini)]

I sent the email to <email address hidden> as suggested.
I also point out that the workaround works only with the Ubuntu stable kernel version (3.11.0-14-generic). In the v.3.13-rc3 produces black screen.

[Alex Barattini (alex.barattini)]

Hi Christopher,
a maintainer of the Linux kernel has written this

Does this patch help?
http://www.spinics.net/lists/linux-acpi/msg47755.html

what should i do

[Alex Barattini (alex.barattini)]

update:
I tried the v3.13-rc5 kernel from the mainline.
Without the workaround acpi_backlight=vendor the adjusting of backlight does not work.
In the other hand, the application of workaround at the v3.13-rc5 kernel produces blackscreen at startup of the OS.

[Alex Barattini (alex.barattini)]

the only version where the workaround works remains the 3.11.0-14-generic (Ubuntu stable kernel)

[penalvch (penalvch)]

Alex Barattini, thank you for advising on the potential fix commit. Regarding it http://www.spinics.net/lists/linux-acpi/msg47755.html , in order to test this patch, start by copying from the line where it notes:
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c

to the last code line before the double dash:
 static int register_count;

Your patch file should be exactly as shown, honoring all spaces, or lack thereof:
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 995e91b..b3032f8 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -85,7 +85,7 @@ module_param(allow_duplicates, bool, 0644);
  * For Windows 8 systems: if set ture and the GPU driver has
  * registered a backlight interface, skip registering ACPI video's.
  */
-static bool use_native_backlight = false;
+static bool use_native_backlight = true;
 module_param(use_native_backlight, bool, 0644);

 static int register_count;

save this file to your Desktop as testfix.patch. Then execute at a terminal:
git config --global user.email "<email address hidden>" && git config --global user.name "Your Name" && git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git ~/Desktop/linux-stable && patch ~/Desktop/linux-stable/drivers/acpi/video.c ~/Desktop/testfix.patch && git add . && git commit

Now in the new window type:
example

press Ctrl+O -> Enter -> Ctrl+X. Then, type at a terminal:
git log -n 1 | grep commit

which should post the commit:
commit <COMMIT>

Use this commit in the below terminal command:
git checkout <COMMIT> && cp /boot/config-`uname -r` .config && yes '' | make oldconfig && make-kpkg clean && CONCURRENCY_LEVEL=`getconf _NPROCESSORS_ONLN` fakeroot make-kpkg --initrd --append-to-version=-custom2 kernel_image kernel_headers && cd .. && sudo dpkg -i *.deb

If for whatever reason the new kernel doesn't boot, it may not be you did something wrong, but just that it won't boot with this commit.

[Aaron Lu (aaron-aalu)]

If testing a patch is not convenient, then use the cmdline option is the same regarding the above patch.
With the latest upstream kernel, add video.use_native_backlight=1 to kernel cmdline and see what happens.

[Alex Barattini (alex.barattini)]

Hi guys,
adding video.use_native_backlight=1 to kernel cmdline produce the solving of the problem on Ubuntu kernel v3.13-rc5.

[Alex Barattini (alex.barattini)]

but does not work in Ubuntu Kernel v3.11.0-14-generic

[Aaron Lu (aaron-aalu)]

The use_native_backlight cmdline option is added to v3.13 kernel so it will not work on v3.11 kernel.

[Alex Barattini (alex.barattini)]

Hi all,
Now that we have identified workarounds ... the bug will be fixed?
Anyway thanks to everyone for the help.

[Alex Barattini (alex.barattini)]

The bug persist on Kernel v3.13-rc6

[Alex Barattini (alex.barattini)]

The bug persist on Kernel v3.13-rc7

[Alex Barattini (alex.barattini)]

The bug persist on Kernel v3.13-rc8

[Alex Barattini (alex.barattini)]

The bug persist on Kernel v3.13-trusty

[Federico Leoni (effelle-gmail)]

A customer of mine gave me his old notebook because he bought a new one. The laptop is running an p to date Xubuntu 13.10 64bit. Now I'm suffering similar issue with brightness control: when I press the appropriate keys on keyboard the slide appears on the upper right corner of the screen but even if it changes the setting has no effect on the system . The notebook I have has an Intel X3100 integrated video

00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 0c)

I tried different combinations on grub but no one resolved the issue. Problem is I have not intel_backlight on /sys/class/backlight folder but just acpi_video0 or dell_backlight (if I set acpi_backlight=vendor on grub).

------------------
effe@Vostro1310:/sys/class/backlight$ for i in /sys/class/backlight/*; do echo -e "\n $i"; cat $i/{brightness,max_brightness,actual_brightness}; done

 /sys/class/backlight/dell_backlight
1
7
1
------------------

If I increase the backlight the files are correctly updated:

------------------
 /sys/class/backlight/dell_backlight
7
7
7
------------------
acpi_listen works just on new mainline kernel 3.13.2 (tried bot generic and lowlatency) on stock kernel there isn't output at all:

video/brightnessup BRTUP 00000086 00000000 K
video/brightnessup BRTUP 00000086 00000000 K
video/brightnessup BRTUP 00000086 00000000 K
video/brightnessdown BRTDN 00000087 00000000 K
video/brightnessdown BRTDN 00000087 00000000 K
video/brightnessdown BRTDN 00000087 00000000 K

Now I'm using xrandr to change the brightness:

effe@Vostro1310:/sys/class/backlight$ xrandr --output LVDS1 --brightness 0.5

What can I try to triage the issue?

Thanks.

[penalvch (penalvch)]

Federico Leoni, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
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.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Federico Leoni (effelle-gmail)]

Christopher,

thanks for your reply. I'll open the new bug ASAP.