MacBook Air display cycles on and off after lid close

Bug #1308818 reported by skierpage on 2014-04-17
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
lightdm (Ubuntu)
Undecided
Unassigned

Bug Description

I have my MacBook Air 5,2 set to
* Security & Privacy > Prompt for password upon Waking from suspend and Returning from blank screen
* Power > When the lid is closed Do nothing.

When I close the lid, the backlight immediately turns off (good!) then after a few seconds it turns on again (noo!) and stays on for around 20 seconds, then the backlight turns off for about 6 seconds, and it continues to cycle on and off. If the brightness is up high it gets very warm and wastes the battery.

What should happen is the backlight should stay off while the lid is closed.

I followed the suggestions at http://superuser.com/questions/462781/how-to-monitor-acpi-events-and-keypresses-in-linux to monitor ACPI events and all I see are two events:

acpid: received input layer event "button/lid LID close"
acpid: rule from 1286[0:0] matched
acpid: notifying client 1286[0:0]
acpid: 1 total rule matched
acpid: completed input layer event "button/lid LID close"

acpid: received input layer event "button/lid LID open"
acpid: rule from 1286[0:0] matched
acpid: notifying client 1286[0:0]
acpid: 1 total rule matched
acpid: completed input layer event "button/lid LID open"

PID 1286 is lightdm, so I'm filing this against lightdm. Maybe when it activates it turns the backlight back on. (But then why does the backlight turn off again?)
I would love to know what else to debug to see what's turning the screen on and off.

Xorg.0.log has
[ 10.496] (II) config/udev: Adding input device Lid Switch (/dev/input/event0)
[ 10.496] (II) No input driver specified, ignoring this device.
[ 10.496] (II) This device may have been added with another device file.
and then no more mention of lid.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: lightdm 1.8.5-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-19.33-generic 3.11.10.5
Uname: Linux 3.11.0-19-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
Date: Wed Apr 16 18:46:34 2014
InstallationDate: Installed on 2012-07-16 (639 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
LightdmConfig:
 [SeatDefaults]
 user-session=ubuntu
 greeter-session=unity-greeter
MarkForUpload: True
SourcePackage: lightdm
UpgradeStatus: Upgraded to saucy on 2013-10-25 (173 days ago)

skierpage (skierpage) wrote :
Andrew Gaul (gaul) wrote :

Duplicate of https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/1311724 ? Workaroundwith a second suspend, i.e., re-opening then closing lid.

skierpage (skierpage) wrote :

Andrew Gaul, I don't think this is related to bug 1311724. Again my settings are

* Security & Privacy > Prompt for password upon Waking from suspend and Returning from blank screen
* Power > When the lid is closed Do nothing.

I don't want my MacBook Air to suspend, just turn off the backlight. Opening and closing the lid does nothing, I just see the lock screen.

So I think the actual sequence is I close lid, the Unity desktop turns off the backlight (good!), then the Ubuntu lock screen (lightdm?) takes over as I requested (good). Lightdm turns the backlight back on (bad) and thereafter does nothing on additional lid close/open events (bad). I don't know what's causing the backlight cycling off and on thereafter.

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