Unable to adjust screen backlight on login screen on Macbook Pro (early 2015)

[user 76543456789]

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu

Fresh install of 16.04.

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center

Don't know. The guide to identify the package told me all login screen issues were "LightDM". ubuntu-bug told me that package was not installed.

3) What you expected to happen

To be able to adjust screen backlight brightness with the dedicated hardware buttons on the login screen, in order to be able log in. This works as expected whenever I'm logged in.

4) What happened instead

I had to log in from an almost black login screen with no backlight.

I believe this bug was present in 15.10 as well.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2
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
CurrentDesktop: Unity
Date: Sun Apr 24 13:58:00 2016
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation Broadwell-U Integrated Graphics [8086:162b] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Apple Inc. Broadwell-U Integrated Graphics [106b:013f]
InstallationDate: Installed on 2016-04-24 (0 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: Apple Inc. MacBookPro12,1
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-21-generic.efi.signed root=UUID=dd7fd213-44e3-45de-afe3-efd8c5825c1e ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/11/2016
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP121.88Z.0167.B16.1602111810
dmi.board.name: Mac-E43C1C25D4880AD6
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro12,1
dmi.chassis.type: 9
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-E43C1C25D4880AD6
dmi.modalias: dmi:bvnAppleInc.:bvrMBP121.88Z.0167.B16.1602111810:bd02/11/2016:svnAppleInc.:pnMacBookPro12,1:pvr1.0:rvnAppleInc.:rnMac-E43C1C25D4880AD6:rvrMacBookPro12,1:cvnAppleInc.:ct9:cvrMac-E43C1C25D4880AD6:
dmi.product.name: MacBookPro12,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
version.compiz: compiz 1:0.9.12.2+16.04.20160415-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.67-1
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
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: Sun Apr 24 02:40:40 2016
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 41002
 vendor APP
xserver.version: 2:1.18.3-1ubuntu2

[Paul White (paulw2u)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. We are sorry that we do not always have the capacity to review all reported bugs in a timely manner.

Ubuntu 16.04 (xenial) reached end-of-standard-support on April 29, 2021.

I'm setting the status of this bug to 'Incomplete' as it's not seen any activity for some time. If this bug report has any relevance when using a currently maintained release of Ubuntu then please let us know which one(s) otherwise this bug report can be left to expire in approximately 60 days time.

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]