Can't change brightness while screen is locked

[luca]

My laptop is configured to lock the screen after X minutes. I lowered the brightness until the point there the backlight is completely off, and after X minutes I wanted to turn the screen again by using the function keys to increase the brightness, but they weren't responding. After a while I realized the screen was blocked, so I blindly type the password, pressed enter and then used the function keys to increase the brightness and it worked.

I think it will be much better if one can change the brightness of the screen even if the screen is locked. I can't see any security problems in allowing that. Optionally, it would be nice if the user can set his lock screen to allow changing the sound volume and other slightly harmless activities one can do with the function or multimedia keys while the screen is locked (is a common thing in the mobile world, I think).

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: xorg 1:7.7+1ubuntu4
ProcVersionSignature: Ubuntu 3.5.0-22.33-generic 3.5.7.2
Uname: Linux 3.5.0-22-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.6.1-0ubuntu9
Architecture: amd64
CheckboxSubmission: f8b82cd9bc23fe075e5068a9824afda5
CheckboxSystem: b1865df84255b8716d3bcc269ff410d1
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom]
CompositorRunning: None
Date: Sun Jan 13 14:43:16 2013
DistUpgraded: 2012-10-28 16:30:42,684 DEBUG enabling apt cron job
DistroCodename: quantal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Toshiba America Info Systems Device [1179:0009]
InstallationDate: Installed on 2012-04-26 (261 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MachineType: TOSHIBA SATELLITE Z830
MarkForUpload: True
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-22-generic root=UUID=36929bf3-a158-44d9-a80d-3adac2840fa8 ro quiet splash acpi_backlight=vendor i915.i915_enable_rc6=1 i915.lvds_downclock=1 vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to quantal on 2012-10-28 (76 days ago)
dmi.bios.date: 07/31/2012
dmi.bios.vendor: TOSHIBA
dmi.bios.version: Version 1.70
dmi.board.asset.tag: 0000000000
dmi.board.name: Portable PC
dmi.board.vendor: TOSHIBA
dmi.board.version: Version A0
dmi.chassis.asset.tag: 0000000000
dmi.chassis.type: 10
dmi.chassis.vendor: TOSHIBA
dmi.chassis.version: Version 1.0
dmi.modalias: dmi:bvnTOSHIBA:bvrVersion1.70:bd07/31/2012:svnTOSHIBA:pnSATELLITEZ830:pvrPT22LE-00300GGR:rvnTOSHIBA:rnPortablePC:rvrVersionA0:cvnTOSHIBA:ct10:cvrVersion1.0:
dmi.product.name: SATELLITE Z830
dmi.product.version: PT22LE-00300GGR
dmi.sys.vendor: TOSHIBA
version.compiz: compiz 1:0.9.8.6-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.39-0ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.0-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.0-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.13.0-0ubuntu6.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.99.99~git20120913.8637f772-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.20.9-0ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.2-0ubuntu3

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[manfreed (manfreed)]

also not only the brightness, but neither of the function keys works on locked screen (like sleep, volume, etc..)

[penalvch (penalvch)]

luca, thank you for reporting this and helping make Ubuntu better. This is reproducible on disparate hardware in Trusty, so this would appear a general issue.

This may be intentional, so for now I'm going to mark this as a Wishlist. I'm not terribly sure the underlying part responsible so I'll leave this to the Ubuntu X team to comment more to this one way or another.

Thank you for your understanding.

[Julian (perlsite)]

I'm affected too. Basically I'm trying to use physical volume knob of external USB DAC to manipulate the volume of the sound.
But since the screen is locked the knob is not working.. till I unlock the screen.

The things become even more frustrating when I use the Power settings and set "Do nothing" option when you close the lid of the laptop. However when I close the lid what's happen is lock the screen (it turns it off, which is OK) but it also disables the external control.

It would be great if sound control is allowed while the screen is locked and also some of the FN+key controls.

P.S. Let me know if there is known workaround (like adding some udev rule, permission or configuration).

[Matt Rae (mattrae)]

Is this a usability issue?

I'd like to be able to turn off the backlight to listen to music in the dark. When I come back to turn the brightness up, the screen is locked and the brightness control doesn't work. I have to blindly enter in my password (yikes?). If I didn't realize that the screen was locked a reset would be the only fix. That doesn't seem very user friendly.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 12.10 (quantal) reached end-of-life on May 16, 2014.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in and change the bug status to Confirmed.