8086:27a2 [Dell Latitude D430] Screen brightness resets to minimized when screen turns off

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

@Bobik-s, and others experiencing this problem... Thanks for reporting this issue.

The primary problem here appears to be the same problem as reported in LP: #872652 ("screensaver backlight stuck off, system looks hung"), for which I have developed a test patch. This PPA supplies an installable gnome-settings-daemon package with the patch applied:

    https://launchpad.net/~kamalmostafa/+archive/gnome-settings-daemon

Please add that PPA to your system, log out and then back in again so that it takes effect, then check your backlight behavior. Does that resolve the problem(s), partially or completely? Post your results to this bug.

Marhaba, Kamal

The problem partially resolved. If the screen goes blank due to the standby then everything is OK and the backlight restores. But if I close the lid (w/o suspend or hybernate) then thebrightness resets to minimum as usual.

@Bobik-s-

Thanks for posting your result with the PPA. Good that it resolves one aspect of the problem at least.

Can you describe in more detail the sequence of events you're doing to get the remaining problem ("the brightness resets to minimum") to occur? When that "reset to minimum" happens, is the screen backlight completely off, or is it just unusually dim? And when it happens, can you then increase the brightness with the brightness-up key, or is it stuck?

To further help us diagnose the issue, please run this command in a terminal window:
  $ ls /sys/class/backlight
It will print one line of output -- please post that line here.

If that line output includes "acpi_video0", then try booting your system with the kernel boot parameter "acpi_backlight=vendor" (which should disable acpi_video0 and attempt to use a different backlight control interface). When you boot with that parameter set, does the behavior change? [ Instructions for using kernel boot parameters are available here: https://wiki.ubuntu.com/Kernel/KernelBootParameters ].

Kamal, here are the answers

sm@D430:~$ ls /sys/class/backlight
dell_backlight intel_backlight

There's no "acpi_video0", so I can't try the instruction you've provided.

The problem with the backlight is the following. The screen of the laptop I use has different levels of brightness and usually I use maximum. But if I do not use the the laptop and close the lid the screen goes blank and after opening the lid again I see that the brighness is minimum and I hardly see anything. It is possible to increase the brightness using the brightness up key but I must admit they don't function properly. That means if you continuously press brightness up key the brightness goes this way: level +1 then minimum then level +1 then minimum then level +1 then minimum and so on... But it is possible to set it to the maximum level again.

@Bobik-s-

Thanks for the detailed explanation.

Next lets try disabling that dell_backlight interface... Please boot with the kernel boot parameter "dell_laptop.backlight=0", verify that only intel_backlight appears when you check "ls /sys/class/backlight", and then test the idle-timeout, lid-close, and brightness keys behavior again. Does disabling dell_backlight help?

I have the same laptop (Dell Latitude D430) as Bobik-s and am experiencing what appears to be the same problem with a fresh install of , so I'll add some more information.

I tried adding the following kernel boot parameters one-by-one:
acpi_backlight=vendor,
acpi_backlight=video
dell_laptop.backlight=0
None of them make any difference. The gnome-settings-daemon PPA didn't appear to make a difference either.

The Fn+Up/Fn+Dn work correctly at the login screen, but only if the screen has not already automatically blanked. If the computer is left at the login screen for ~10 minutes, then it will automatically blank. Move the mouse and the backlight returns to partial brightness, but Fn+Up/Fn+Dn do nothing.

System Settings -> Screen contains a slider to adjust screen brightness. If I first click on it with the mouse, I can then use the Left and Right arrow keys to move the slider back and forth. After every 4 or 5 presses of the left (or right) arrow key, the brightness changes, alternating between brighter or dimmer. At either end of the slider the screen brightness appears to alternate between minimum and maximum. When the slider is 1 / 4 of the way across, the brightness alternates between 25% and 75%. When the slider is near the middle, the alternations are barely perceptible – perhaps between 40% and 60%

A question about something which may be related—the battery indicator at the top of the screen is always visible, even when plugged in. Isn't it supposed to disappear or change to indicate that it is running on AC? Clicking on the indicator shows “Battery (charged)”. Removing the power cord changes the text to “Battery (1:50 left)”.

The X driver doesn't control brightness. Might be an issue in the userspace daemon. Or some ACPI quirkiness.

Possibly dupe of 872932... similar symptoms around the same time frame.

I have the same problem on a Dell D830, Intel graphics, on Oneiric.

The brightness when returning from screensaver is at minimum (xbrightness shows level 0), brightness keys work and so does xbrightness -set 100.

Brightness control worked fine for me on Natty.

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

I replaced Ubuntu with a clean install of Lubuntu 11.10 on the same laptop and adjusting the screen brightness works perfectly.

It's not merely gnome related. I've ran away from gnome3 and both kubuntu and xubuntu 11.10 suffer from this bug on my dell D630. Didn't have this problem with either DE on 11.04.

Hi,

I can confirm that this is not restricted to gnome.

I'm running Kubuntu Oneric on a Dell D630 and have the exact same problem (screen brightness is minimum after display is switched on again). This is the case in KDE and KDM. I also installed ubuntu-desktop and observed the same behavior with unity. Also everything was fine on Natty.

Regards, Matthias

After updating the system to the new kernel 3.0.0.15-generic the problem was partially resolved. Now the system remebers your choice of screen brightness level. You don't have to re-adjust it every time you waku up the system. But still screen adjustment control works wierdly - if you repeatedely goes from min to max step by step the real level of brightness goes min-max with every button press. So it's possible to fix it but in an unlogical way.

@Bobik-s and others experiencing this problem-

For reference, the bug noted in the bug report title is actually a duplicate of bug 872652 (and glad to hear that 3.0.0-15 fixes it for you, Bobik-s).

I have prepared a PPA test kernel for Ubuntu 11.10 (Oneiric) including a patch which might address the remaining "min/max on every step" problem:

    https://launchpad.net/~kamalmostafa/+archive/inverted-backlight

Feedback to this bug report will be appreciated.

The bug competely resolved with generic kernel 3.2.4 update. We may close it

Bobik-s, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

Also, could you please test the latest upstream kernel available (not the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.13-rc3

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]