[Dell Latitude 3450] Brightness cannot be adjusted on 14.04

[Po-Hsu Lin]

CID: 201407-15273 Dell Latitude 3450

The brightness key does not work on this system, but the brightness level indicator will change with the key press event.
It can't be adjusted with the "Brightness and Lock" applet as well.

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/controlC1: ubuntu 1675 F.... pulseaudio
 /dev/snd/controlC0: ubuntu 1675 F.... pulseaudio
CRDA:
 country TW:
  (2402 - 2472 @ 40), (3, 27)
  (5270 - 5330 @ 40), (3, 17), DFS
  (5735 - 5815 @ 40), (3, 30)
CurrentDesktop: Unity
CurrentDmesg:
 [ 18.758040] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
 [ 25.952714] init: plymouth-upstart-bridge main process ended, respawning
 [ 25.965016] init: plymouth-upstart-bridge main process ended, respawning
Date: Sun Oct 12 23:19:23 2014
HibernationDevice: RESUME=UUID=cc661c2c-2753-48af-a7b7-2e488e0d3104
InstallationDate: Installed on 2014-10-13 (0 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Dell Inc. Latitude 3450
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-37-generic root=UUID=47399cd3-9a2c-4133-b667-251caf01c578 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: 07/24/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: T40
dmi.board.name: 013C61
dmi.board.vendor: Dell Inc.
dmi.board.version: X03
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrT40:bd07/24/2014:svnDellInc.:pnLatitude3450:pvr01:rvnDellInc.:rn013C61:rvrX03:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude 3450
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Po-Hsu Lin (cypressyew)]

Verified with 3.16.0-031600-generic #201408031935
This issue does not exist with this kernel.

Also, brightness control could work with the "video.use_native_backlight=1" kernel parameter on 3.13 kernel.