Screen dims and brightens randomly

[a.sweets]

Binary package hint: linux-source-2.6.22

I have a Dell 1420n laptop. When on battery power, my screen will dim and brighten rather randomly. The most common occurance is if I don't touch my laptop for about 1 minute, the screen will dim much like in Mac OSX, however, when I touch the mouse, the brightness fails to return to whatever I had it set at.

Another example: I had my screen dimmed down to about 50% to conserve battery and after about 1 minute of not doing anything with my computer, it randomly returned to 100% brightness. After it happened, to test it, I repeated the process of dimming to 50% and not touching the keyboard or mouse for 1 minute and the screen returned to 100% brightness.

The screen will also 'do it's own thing' as far as brightness when I'm doing just about anything, it will randomly decide to dim or brighten. It seems like it will do it a lot in a short period of time and then not do it at all for a while.

These are my power settings for battery power:
(As soon as I opened my power manager, my screen returned to 100% brightness just now. :-/ )

Put computer to sleep: Never
When laptop lid is closed: Suspend
When battery power is critically low: Shutdown
Put display to sleep when inactive for: 10 min
Dim brightness by: 0%
Dim display when idle box: unchecked

An aside: when on A/C power, I have the 'dim display when idle' box checked, and the dimming function works fine and will return to 100% or previous brightness when the mouse or keyboard is touched.

For other models of computers with this problem, see thread in Ubuntu forums:
http://ubuntuforums.org/showthread.php?t=595211

I'll refer them here as well to report their own confirmations.

[Jameson Finney (jrfdf245)]

I have the exact same problem on my Hp Pavillion dv6000t. This problem started shortly after I upgraded to Gutsy Gibson. Interestingly enough my screen dimmed the moment that I opened Gnome power manager. My power settings are as follows:

Put computer to sleep: Never
When laptop lid is closed: Blank Screen
When battery power is critically low: Shutdown
Put display to sleep when inactive for: 16 min
Dim brightness by: 70%
Dim display when idle box: checked

Note: I am using the restricted NVIDIA driver.
Additional information can be supplied if needed.

[a.sweets (a-sweets)]

Does this happen for you on A/C power, on battery power, or both?

Also, are those power settings for when on battery power or A/C?

[Jameson Finney (jrfdf245)]

I have not been tracking it that closely, but I believe it occurs in both modes. The settings I provided were for battery mode. The following settings are for AC mode:

Put computer to sleep when inactive for: Never
When laptop lid is closed: Blank screen
Put display to sleep when inactive for: 41 minutes
Set display brightness to: %100
Dim display when idle: unchecked

[a.sweets (a-sweets)]

Hmm.

I guess I should have gathered that those were your battery settings since you included "When battery power is critically low..." lol.

Anyway, I don't know what's going on/how to fix it, hence this bug report....help anyone?

I can provide any additional information that could possibly be helpful.

[Jameson Finney (jrfdf245)]

I have just observed this event occurring under AC power.

[a.sweets (a-sweets)]

I'm not sure what else to do at this point.
:-\

At least it's not a debilitating bug.

[muszek (muszek)]

I'm pretty sure I have the same bug and at least I know the workaround - take a look at post #2 @ https://bugs.launchpad.net/ubuntu/+bug/162633 (it appears to be the same bug, could be marked as duplicate).

[Leann Ogasawara (leannogasawara)]

I'm retargeting this bug towards the upcoming Hardy kernel and have tagged it as "hardy-kernel-candidate". However against the linux-source-2.6.22 package this is being marked as "Won't Fix" as it does not meet the criteria for a stable release update. To learn more about the stable release update process please refer to https://wiki.ubuntu.com/StableReleaseUpdates . Thanks!

[Toby Bartels (tobybartels)]

I have the same problem, on a Dell Inspiron E1505. It appeared immediately after upgrading from Feisty to Gutsy.

I almost always have AC power, and my Power Management settings include:
* Put display to sleep when inactive for: 40 minutes (default, unchanged);
* Set display brightness to: 0% (changed from default 100%);
* Dim display when idle: unchecked (I forget the default).
If I need a brighter screen, then I like to brighten it from the keyboard, which on this machine uses Fn-Up and Fn-Down. This gives me a little picture, just like the one I get when I adjust the volume from the keyboard, showing my adjustment on a sliding scale. It also does change the actual brightness.

Ten minutes later, regardless of what I'm doing or have done, the brightness goes back down to the lowest setting. I can make this happen earlier by opening the Power Management settings. If I change Power Management's "Set display brightness to" setting, then this is what the brightness will change to after 10 minutes.

[Leann Ogasawara (leannogasawara)]

The Hardy Heron Alpha2 release will be coming out soon (around Dec 20). It will have an updated version of the kernel. It would be great if you could test with this new release and verify if this issue still exists. I'll be sure to update this report when Alpha2 is available. Thanks!

[Leann Ogasawara (leannogasawara)]

Hardy Heron Alpha2 was recently released. It contains an updated version of the kernel. You can download and try the new Hardy Heron Alpha2 release from http://cdimage.ubuntu.com/releases/hardy/alpha-2/ . You should be able to then test the new kernel via the LiveCD. If you can, please verify if this bug still exists or not and report back your results. General information regarding the release can also be found here: http://www.ubuntu.com/testing/hardy/alpha2 . Thanks!

[Travis Abram (inthought)]

My laptop shows similar patterns. Most noticeable is when on battery power; mouse movement seems to change the brightness based on activity.

[muszek (muszek)]

@Leann Ogasawara
I've just tested Hardy Alpha 3 and the bug still exists, but it happens less often. I used the live cd for 50 minutes and the spontaneous change in brightness happened just once (around 48th minute).
Let me say once again what happens on my machine (I've said it somewhere else...).
 * "unwanted changes" - brightness _always_ changes to the value of "Set display brightness to:" slider in "On AC Power" tab in gnome-power-preferences. If current brightness == the value of this slider, then brightness doesn't change.
 * "unwanted changes are triggered by"
 ** opening of gnome-power-preferences (instant change of brightness) - both gutsy and hardy
 ** spontaneous change (user doesn't have to do anything). every XXX seconds in gutsy, once in 50 minutes in hardy

The workaround is to use that slider for adjusting the brightness... I've been doing it ever since gutsy was released and it's not that annoying.

[Sebastien Bacher (seb128)]

Thanks for the bug report. This particular bug has already been reported, but feel free to report any other bugs you find.

[Toby Bartels (tobybartels)]

Where has this already been reported? Should this be marked as a duplicate?

[ali_deren (ali-deniz-eren)]

Then.. Is there any way to fasten brightness up manually? I mean how I can prevent gnome to manage the screen brightness..

Thank you..

[Anonymous (unquoteveracity-deactivatedaccount)]

@ali_deren - Yes, use the brightness applet (right click on a panel > click add to panel > select the brightness applet) to control brightness. Only the brightness applet "fastens" the brightness level.