Comment 0 for bug 1197482

After installing Raring on my 2013 MacBook Air 6,2, I find that sometimes when resuming from suspend, the screen is dark. I have tracked this down to the i915 driver, where the screen brightness can be adjusted between levels 0-15. This works correctly after boot, with 0 being dark and 15 the brightest.

Sometimes after suspend/resume, the screen is equally dark between levels 0-12, and seems to be equally bright for levels 13-15 (brightest). I say sometimes, because it's not every time. It _might_ be after the second or third suspend/resume, but I'm not yet sure how to repeat it.

When this happens, I have to kill lightum, the backlight/keyboard monitoring daemon, and manually set the brightness using the sys filesystem:

echo '15' | sudo tee /sys/devices/pci0000\:00/0000\:00\:02.0/backlight/acpi_video0/brightness

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: linux-image-3.8.0-25-generic 3.8.0-25.37
ProcVersionSignature: Ubuntu 3.8.0-25.37-generic 3.8.13
Uname: Linux 3.8.0-25-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: linus 1939 F.... pulseaudio
CRDA:
 country SE:
  (2402 - 2482 @ 40), (N/A, 20)
  (5170 - 5250 @ 40), (N/A, 20)
  (5250 - 5330 @ 40), (N/A, 20), DFS
  (5490 - 5710 @ 40), (N/A, 27), DFS
Date: Wed Jul 3 19:23:53 2013
HibernationDevice:
 RESUME=/dev/mapper/cryptswap1
 #RESUME=UUID=7625120b-1951-4a58-8da6-1c47db358631
MachineType: Apple Inc. MacBookAir6,2
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-25-generic root=UUID=2f08800d-d161-46e7-87b6-0f88e86890af ro i915.i915_enable_rc6=3 libata.force=1:noncq resume=/dev/sda4 quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.8.0-25-generic N/A
 linux-backports-modules-3.8.0-25-generic N/A
 linux-firmware 1.106
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/24/2013
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBA61.88Z.0099.B00.1305241529
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-7DF21CB3ED6977E5
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookAir6,2
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-7DF21CB3ED6977E5
dmi.modalias: dmi:bvnAppleInc.:bvrMBA61.88Z.0099.B00.1305241529:bd05/24/2013:svnAppleInc.:pnMacBookAir6,2:pvr1.0:rvnAppleInc.:rnMac-7DF21CB3ED6977E5:rvrMacBookAir6,2:cvnAppleInc.:ct10:cvrMac-7DF21CB3ED6977E5:
dmi.product.name: MacBookAir6,2
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.