Comment 0 for bug 1341988

CID: 201403-14888 Dell Inspiron 11 - 3147

The screen brightness cannot be controlled by the hotkey.

Steps:
1. Install 14.04 + update (3.13.0-30), boot to desktop
2. Try to control brightness with the hotkey
3. Try to control brightness with "Brightness and Lock" applet

Expected result:
* Brightness could be controlled by the hotkey

Actual result:
* Brightness level indicator changed along with the hotkey, but the brightness won't change

Debugging information:
ubuntu@201403-14888:~$ grep -r . /proc/acpi
/proc/acpi/button/lid/LID0/state:state: open
/proc/acpi/wakeup:Device S-state Status Sysfs node
/proc/acpi/wakeup:XHC1 S0 *enabled pci:0000:00:14.0
/proc/acpi/wakeup:RP01 S4 *disabled pci:0000:00:1c.0
/proc/acpi/wakeup:PXSX S4 *disabled
/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
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:PWRB S4 *enabled
/proc/acpi/wakeup:LID0 S3 *enabled

ubuntu@201403-14888:~$ ls /sys/class/backlight/
acpi_video0 intel_backlight

ubuntu@201403-14888:~$ dmesg | grep 'ACPI: Video'
[ 10.409549] ACPI: Video Device [PEGP] (multi-head: yes rom: no post: no)
[ 10.435109] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-30-generic 3.13.0-30.55
ProcVersionSignature: Ubuntu 3.13.0-30.55-generic 3.13.11.2
Uname: Linux 3.13.0-30-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1563 F.... pulseaudio
CRDA:
 country TW:
  (2402 - 2472 @ 40), (3, 27)
  (5270 - 5330 @ 40), (3, 17), DFS
  (5735 - 5815 @ 40), (3, 30)
CurrentDesktop: Unity
Date: Tue Jul 15 02:04:08 2014
HibernationDevice: RESUME=UUID=b30f45e9-6fc7-4aa0-adff-37e7c87c19cd
InstallationDate: Installed on 2014-07-15 (0 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
MachineType: Dell Inc. Inspiron 11 - 3147
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-30-generic.efi.signed root=UUID=cc246aa9-85c1-49ac-b06b-6c0f4e37dbea ro quiet splash
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-30-generic N/A
 linux-backports-modules-3.13.0-30-generic N/A
 linux-firmware 1.127.4
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/05/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 00K010
dmi.board.vendor: Dell Inc.
dmi.board.version: D02
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A01
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd05/05/2014:svnDellInc.:pnInspiron11-3147:pvr:rvnDellInc.:rn00K010:rvrD02:cvnDellInc.:ct8:cvrA01:
dmi.product.name: Inspiron 11 - 3147
dmi.sys.vendor: Dell Inc.