settings lack slider to adjust screen brightnes

[Evaristo Sourdis]

xorg was suggested by system, I'm not sure, Thanks a lot!

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-28.47-generic 4.4.13
Uname: Linux 4.4.0-28-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Thu Jun 30 11:56:41 2016
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] RS480M [Mobility Radeon Xpress 200] [1002:5955] (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company RS480M [Mobility Radeon Xpress 200] [103c:3085]
InstallationDate: Installed on 2016-06-20 (10 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
Lsusb:
 Bus 001 Device 002: ID 0bda:8179 Realtek Semiconductor Corp. RTL8188EUS 802.11n Wireless Network Adapter
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: Hewlett-Packard Pavilion ZV6100 (EC356UA#ABA)
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-28-generic root=UUID=16cac4e3-e299-44cf-9a9e-0afed08ab81b ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/24/2006
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.1C
dmi.board.name: 3085
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 42.3B
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.1C:bd08/24/2006:svnHewlett-Packard:pnPavilionZV6100(EC356UA#ABA):pvrF.1C:rvnHewlett-Packard:rn3085:rvr42.3B:cvnHewlett-Packard:ct10:cvrN/A:
dmi.product.name: Pavilion ZV6100 (EC356UA#ABA)
dmi.product.version: F.1C
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.12.2+16.04.20160526-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.67-1ubuntu0.16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.2.0-1ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.2.0-1ubuntu2
version.xserver-xorg-core: xserver-xorg-core 2:1.18.3-1ubuntu2.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2
xserver.bootTime: Thu Jun 30 11:51:50 2016
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.18.3-1ubuntu2.2
xserver.video_driver: radeon