I'm running Ubuntu 11.04, and I have a hp dm3z laptop with an external 22" monitor.
I have it set to extended desktop, with the external screen to the left of the laptop. The external screen has a resolution of 1680x1050, and the laptop has a resolution of 1366x800.
I noticed daily that it would reset my desktop to mirrored display, with a resolution of 800x600. I tracked down the cause to be the mlocate script within cron.daily (rant: really annoying), where the underlying cause was on_ac_power, and specifically the command
cat /sys/class/power_supply/AC/online
starts going through the cycle of different desktop layouts.
When in the layout of external to left of laptop screen, with each successive call to 'cat /sys/class/power_supply/AC/online',
it goes to the following layouts, in this order:
mirrored (800x600)
laptop screen on left side of extended desktop, external on right (both at correct resolutions)
laptop screen only (correct resolution)
external monitor only (correct resolution)
external monitor on left, laptop screen on right (both at correct resolution)
I've also noticed that if I unplug my AC power while the external monitor is plugged in, and unplug the external monitor (because I move my laptop), it seems to go through at least one full cycle before it finally settles on laptop only, but it takes a good few seconds (and it's very, very noticeable).
This happens when the external monitor is plugged into the HDMI port or the VGA port.
Additionally, this also happens if I run 'cat < /sys/class/power_supply/AC/online'
When on battery power, it outputs '0', when on AC power, it outputs '1'.
I've run Ubuntu 11.10 (but decided to downgrade for other reasons) and this problem still persists there.
Please let me know if there's any other information I can provide.
If it wasn't obvious, I don't expect my monitors to cycle through the different possible output modes because of a daily cron script. Instead, it does happen. It's really annoying. Now that I've found it, I can disable the cron script, but it was really annoying to track down.
brian@nevada:/etc/cron.daily$ lsb_release -rd
Description: Ubuntu 11.04
Release: 11.04
brian@nevada:/etc/cron.daily$ uname -a
Linux nevada 2.6.38-13-generic #52-Ubuntu SMP Tue Nov 8 16:53:51 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
brian@nevada:/etc/cron.daily$ lspci | grep -i radeon
01:05.0 VGA compatible controller: ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics]
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: amd64
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: SB [HDA ATI SB], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: brian 1631 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
Card hw:0 'SB'/'HDA ATI SB at 0xf2300000 irq 16'
Mixer name : 'IDT 92HD81B1C5'
Components : 'HDA:111d76d5,103c3656,00100402'
Controls : 14
Simple ctrls : 9
Card1.Amixer.info:
Card hw:1 'HDMI'/'HDA ATI HDMI at 0xf2210000 irq 19'
Mixer name : 'ATI RS690/780 HDMI'
Components : 'HDA:1002791a,00791a00,00100000'
Controls : 4
Simple ctrls : 1
Card1.Amixer.values:
Simple mixer control 'IEC958',0
Capabilities: pswitch pswitch-joined penum
Playback channels: Mono
Mono: Playback [on]
DistroRelease: Ubuntu 11.04
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
MachineType: Hewlett-Packard HP Pavilion dm3t Notebook PC
Package: linux (not installed)
ProcEnviron:
LANGUAGE=en_US:en
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-13-generic root=UUID=11e1ee27-f55d-4452-b0d7-65dcd73522ca ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 2.6.38-13.52-generic 2.6.38.8
RelatedPackageVersions:
linux-restricted-modules-2.6.38-13-generic N/A
linux-backports-modules-2.6.38-13-generic N/A
linux-firmware 1.52.4
Tags: natty
Uname: Linux 2.6.38-13-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
dmi.bios.date: 09/20/2009
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.09
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 3656
dmi.board.vendor: Flextronics
dmi.board.version: 44.18
dmi.chassis.type: 10
dmi.chassis.vendor: Flextronics
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.09:bd09/20/2009:svnHewlett-Packard:pnHPPaviliondm3tNotebookPC:pvr03A0100000240010110120000:rvnFlextronics:rn3656:rvr44.18:cvnFlextronics:ct10:cvrN/A:
dmi.product.name: HP Pavilion dm3t Notebook PC
dmi.product.version: 03A0100000240010110120000
dmi.sys.vendor: Hewlett-Packard
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