[Dell Latitude E5550] Brightness control does not work on this system

[Po-Hsu Lin]

CID: 201406-15271 Dell Latitude E5550

Brightness control does not work on this system
The brightness level indicator would change with hotkey events, but the brightness itself does not.

Debugging information:
ubuntu@201406-15271:~$ ls /sys/class/backlight
acpi_video0 intel_backlight

ubuntu@201406-15271:~$ grep -r . /proc/acpi
/proc/acpi/battery/BAT0/alarm:alarm: unsupported
/proc/acpi/battery/BAT0/state:present: yes
/proc/acpi/battery/BAT0/state:capacity state: ok
/proc/acpi/battery/BAT0/state:charging state: discharging
/proc/acpi/battery/BAT0/state:present rate: 772 mA
/proc/acpi/battery/BAT0/state:remaining capacity: 3170 mAh
/proc/acpi/battery/BAT0/state:present voltage: 12493 mV
/proc/acpi/battery/BAT0/info:present: yes
/proc/acpi/battery/BAT0/info:design capacity: 3540 mAh
/proc/acpi/battery/BAT0/info:last full capacity: 3372 mAh
/proc/acpi/battery/BAT0/info:battery technology: rechargeable
/proc/acpi/battery/BAT0/info:design voltage: 11100 mV
/proc/acpi/battery/BAT0/info:design capacity warning: 354 mAh
/proc/acpi/battery/BAT0/info:design capacity low: 107 mAh
/proc/acpi/battery/BAT0/info:cycle count: 0
/proc/acpi/battery/BAT0/info:capacity granularity 1: 35 mAh
/proc/acpi/battery/BAT0/info:capacity granularity 2: 35 mAh
/proc/acpi/battery/BAT0/info:model number: DELL 9P4D246
/proc/acpi/battery/BAT0/info:serial number: 226
/proc/acpi/battery/BAT0/info:battery type: LiP
/proc/acpi/battery/BAT0/info:OEM info: LGC-LGC3.4
/proc/acpi/button/lid/LID0/state:state: open
/proc/acpi/ac_adapter/AC/state:state: off-line
/proc/acpi/wakeup:Device S-state Status Sysfs node
/proc/acpi/wakeup:PEG0 S4 *disabled
/proc/acpi/wakeup:PEGP S4 *disabled
/proc/acpi/wakeup:PEG1 S4 *disabled
/proc/acpi/wakeup:PEGP S4 *disabled
/proc/acpi/wakeup:PEG2 S4 *disabled
/proc/acpi/wakeup:PEGP S4 *disabled
/proc/acpi/wakeup:RP01 S4 *disabled pci:0000:00:1c.0
/proc/acpi/wakeup:PXSX S4 *disabled pci:0000:01:00.0
/proc/acpi/wakeup:RP02 S4 *disabled
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP03 S4 *disabled
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP04 S4 *disabled pci:0000:00:1c.3
/proc/acpi/wakeup:PXSX S4 *disabled pci:0000:02:00.0
/proc/acpi/wakeup:RP05 S4 *disabled pci:0000:00:1c.4
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP06 S4 *disabled
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP07 S4 *disabled
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP08 S4 *disabled
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:GLAN S4 *disabled pci:0000:00:19.0
/proc/acpi/wakeup:EHC1 S0 *enabled pci:0000:00:1d.0
/proc/acpi/wakeup:EHC2 S0 *disabled
/proc/acpi/wakeup:XHC S0 *enabled pci:0000:00:14.0
/proc/acpi/wakeup:HDEF S4 *disabled pci:0000:00:1b.0
/proc/acpi/wakeup:LID0 S3 *enabled
/proc/acpi/wakeup:PBTN S3 *enabled

ubuntu@201406-15271:~$ dmesg | grep 'ACPI: Video'
[ 12.986933] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)
ubuntu@201406-15271:~$

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-37-generic 3.13.0-37.64
ProcVersionSignature: Ubuntu 3.13.0-37.64-generic 3.13.11.7
Uname: Linux 3.13.0-37-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1530 F.... pulseaudio
 /dev/snd/controlC1: ubuntu 1530 F.... pulseaudio
CurrentDesktop: Unity
Date: Wed Oct 15 23:03:45 2014
HibernationDevice: RESUME=UUID=02cbc1f1-a261-484c-8fc2-05b68f73446d
InstallationDate: Installed on 2014-10-09 (6 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Dell Inc. Latitude E5550
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-37-generic root=UUID=d3b20ae5-9ff8-49b3-b640-1c6a9f264710 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-37-generic N/A
 linux-backports-modules-3.13.0-37-generic N/A
 linux-firmware 1.127.7
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/25/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: T43
dmi.board.name: 0141B2
dmi.board.vendor: Dell Inc.
dmi.board.version: X02
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrT43:bd07/25/2014:svnDellInc.:pnLatitudeE5550:pvr01:rvnDellInc.:rn0141B2:rvrX02:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E5550
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Anthony Wong (anthonywong)]

@PHLin
Can you verify this bug with a mainline kernel? This bug should have been fixed in kernels since 3.16.

[Po-Hsu Lin (cypressyew)]

Hello,
Yes it works with 3.16.0-031600-generic #201408031935

[Anthony Wong (anthonywong)]

So this bug is now fixed in utopic with 3.16 kernel. If you agree, I'd like to close this bug.

[Po-Hsu Lin (cypressyew)]

Yes,
but it will be great if it could pass with 3.13 kernel,
in that case, we won't need to deal with the kernel upgrade issue like what we're dealing with recently (3.5 / 3.8 / 3.11 -> 3.13)

However, we should wait and see how many blocker would be solved on this system, then we decide if it's worth to fix it in 3.13.