Unable to change screen brightness

[QT]

Using Fn+F4 or Fn+F5, the screen brightness does not change.

I have BIOS A07 and the Sputnik PPAs

Also the System Settings control does not actually change the brightness.

In both cases there is an on-screen pop-up to show what the setting _should_ be, but no actual change happens.

[Kyle Fazzari (kyrofa)]

Try changing the brightness with those keys and run

$ cat /sys/class/backlight/acpi_video0/brightness

each time. Does that value actually change?

[QT (quitetall)]

After quite a few hours, Update Manager told me that there were some updates, and a restart later its now working.

So maybe chalk this one down to not getting updates notified? Although 6 or more hours is quite a while :-)

[MikeCamel (mike-hingston)]

This should work fine with the packages from the PPA: https://launchpad.net/~canonical-hwe-team/+archive/sputnik-kernel (as per last comment).

SUGGEST CLOSE.

[Tristan Schmelcher (tschmelcher)]

I am still experiencing this with all updates installed. The PPA you linked to is not configured by default on the Dell XPS 13 Developer Edition, so I think this bug should be considered open until the fix reaches users.

[Kent Baxley (kentb)]

This is the main backlight tracking bug:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/954661

[Kyle Fazzari (kyrofa)]

Tristan, that PPA should indeed be enabled. If it's not, please try doing so, get all updates, and post back here with your progress.

[Tristan Schmelcher (tschmelcher)]

Huh, so Dell was supposed to ship the XPS 13 DE devices with that PPA pre-installed? Guess I will inform them of their mistake.

Do you know if there is an authoritative list of what was supposed to be shipped on the XPS 13 DE devices? This isn't the first thing that was wrong on mine.

[Tristan Schmelcher (tschmelcher)]

(Confirmed that the PPA does of course fix the problem.)

[Daniel Farina (drfarina)]

This has regressed for me as of late, after working for some time. Quantal. uname -a:

Linux sputnik 3.5.0-25-generic #38+kamal13~DellXPS-Ubuntu SMP Tue Feb 19 23:00:06 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

[Toby Isaac (toby-isaac)]

This has regressed for me as well.

Linux tisaac-laptop 3.2.0-38-generic #61+kamal14~DellXPS-Ubuntu SMP Fri Feb 22 19:27:08 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

[Tristan Schmelcher (tschmelcher)]

Confirmed. Note that it's only broken after doing suspend/resume once. Also being discussed at http://en.community.dell.com/techcenter/os-applications/f/4613/t/19492924.aspx

[Marcus D. Hanwell (cryos)]

I just got a Sputnik 2 laptop and don't have that PPA enabled as far as I can tell http://opensource.dell.com/releases/sputnik/archive is the only sputnik specific source. I installed KDE and find issues in setting the brightness from the graphical controls (although the function keys seem to work as expected). I applied all updates but have not added/removed any PPAs yet.

$ uname -a
Linux deuterium 3.2.0-38-generic #61-Ubuntu SMP Tue Feb 19 12:18:21 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

[Marcus D. Hanwell (cryos)]

I can also confirm that after a reboot the screen brightness/dimming works fine from KDE. There are some minor issues with the OSD not showing up, but other than that.

[Kent Baxley (kentb)]

Dell has also published a knowledgebase article on the brightness keys:

http://www.dell.com/support/troubleshooting/us/en/04/KCS/KcsArticles/ArticleView?c=us&l=en&s=bsd&docid=590117

[Tristan Schmelcher (tschmelcher)]

@Marcus Dell seems to be shipping the Sputnik devices with an incomplete set of PPAs. IIUC, the full set should be:

http://opensource.dell.com/releases/sputnik/archive
http://dell.archive.canonical.com/updates/
http://ppa.launchpad.net/canonical-hwe-team/sputnik-kernel/ubuntu
http://ppa.launchpad.net/canonical-hwe-team/sputnik-policykit/ubuntu

My machine was missing the second two.

[Kent Baxley (kentb)]

sputnik-policykit is not required on the preloads since the dell base image for all pre-loaded machines turns hibernate on in the UI by default.

[Tristan Schmelcher (tschmelcher)]

Good to know, thanks!

[Tristan Schmelcher (tschmelcher)]

FYI, I've filed bug 1154429 for the missing sputnik-kernel PPA.

[Daniel Farina (drfarina)]

This has regressed for me in Raring, which has no PPA'd kernel. This workaround, reported from other places, works:

sudo bash -c '/bin/echo 0 > /sys/class/backlight/intel_backlight/brightness'

I mentioned my ask for a Raring PPA in https://bugs.launchpad.net/dell-sputnik/+bug/1166552

[Kent Baxley (kentb)]

@Daniel,

Some fixes were committed to Raring's kernel to further iron out the backlight problems...hopefully there won't be many more (if any) :-)

See: https://bugs.launchpad.net/dell-sputnik/+bug/1169376/comments/26

@Tristan & others:

We've pushed out an online update for those that don't have the sputnik-kernel ppa configured yet:

https://bugs.launchpad.net/dell-sputnik/+bug/1154429/comments/2

As far as PPA's go, the only relevant ones that need to be installed are:

http://dell.archive.canonical.com/updates/
http://ppa.launchpad.net/canonical-hwe-team/sputnik-kernel/ubuntu

[Kent Baxley (kentb)]

12.04-specific issues should now be ironed out as long as folks are running the sputnik kernels from the ppa. Pre-loaded machines should also be pulling in a fix to connect them to the sputnik ppa if they aren't set up already.

For 13.04 backlight problems, we're currently tracking that here:

https://bugs.launchpad.net/dell-sputnik/+bug/1169376

Results tend to be hit and miss for different users, although the latest 13.04 kernel is supposed to be fixing the brightness adjustment problems.