How do I deactivate dynamic contrast on a Dell XPS?

Question

I am experiencing annoying automatic backlight brightness changes under ubuntu 12.04 LTS on my Dell XPS ultrabook.

It seems to be connected to the amount of white pixels on the screen (switching back an forth between dark/light application windows makes the effect noticable, but also just scrolling through a website.) So I think it is the dynamic contrast feature of the notebook screen.

How do I turn this off in Ubuntu? Windows offers specific Intel driver options for this, but I can't find any for Ubuntu.

Model: Dell XPS 14 Ultrabook and currently running Unity

Solution

Reproduced on a Dell XPS 13^[1], there seem to be a real problem stemming from a collision between the graphics drivers, constantly calling the screen's brightness auto-adjust and causing the screen to flicker. See this bug report on another related issue (regarding broken functionality of function keys out of the box) that suggests a solution to the flickering problem as well;

The fix to both issues is offered by Kamal Mostafa from the Canonical Hardware Enablement Team as part of the Sputnik ^[2] Kernel PPA, while an independent earlier patch targets the function keys issue only (it is best, of course, to update with the former).

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^[1] I happen to own an XPS 13 model, and incidentally installed the 12.04 the day I got it... This is not a Sputnik machine, however (see ^[2]).

^[2] The Sputnik project was Dell's effort to market a developer oriented edition of the Dell XPS 13 laptop, pre-installed with Ubuntu 12.04, and packed with developer-targeted goodies

Comments

[Admin]

could you please provide with the exact model of your Laptop and your Window Manager? (KDE,Unity?)

[Admin]

@Jorge, please respect the post content, this question is referring to a Dell XPS 14, so your edit for the title is redundant.

[Admin]

Sorry, I was cleaning up the Dell XPS 13 questions and made a mistake!

[Rock]

No options in BIOS, none in Unity performance or energy options either. I think it is a driver flag/signal (independent from the current backlight value) but I don't know where to look for the correct one. Nvidia card is turned off by bumblebeee.

[JGleason]

turn it back on, the Nvidia-settings might help you

[Rock]

I have an Nvidia-Optimus GPU here, that means all my graphics are routed through the intel GPU and therefore I cannot access the nvidia settings correctly (driver not "really" active). So that does not help :-/

[david_adler]

could somebody link me to how some instructions with how to install the Sputnik Kernel PPA from launchpad.net as linked above

[Eliran Malka]

sorry, @david_adler, i didn't actually installed that kernel, just patched the existing kernel, so i have no clue how to install it.

[david_adler]

@EliranMalka that's what I want to do also. Tried sudo add-apt-repository ppa:canonical-hwe-team/sputnik-kernel and then sudo apt-get update but no luck. How did you patch the kernel?

[Eliran Malka]

i just followed the instructions, i suppose. but the problem had been fixed since, you should be fine with the stock kernel in 13.* versions.