Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

After a fresh install of Ubuntu, I discovered the function keys for screen brightness control (Fn+F4 and Fn+F5 in that case) are not functioning. Digging around here, I managed to get them to work by following a solution suggested on several posts, but alas — after applying it, a strange problem occurred:

When setting the brightness level to any value other than minimum or maximum, the screen starts flickering back and forth from the selected level to full brightness, apparently due to Dell's power saver attempting to dim the screen to auto-adjust brightness levels.

I looked up for a solution here on the site, and possibly everywhere, with no avail. Also tried:

  • To manually control the brightness by configuring the ACPI level (setting values by echo [some_value] | sudo tee /sys/class/backlight/[vendor]_backlight/[some_key], without success.
  • Installing the Intel graphics driver, thinking it's missing. Realized it's installed out of the box by installing Mesa Utils.

How to resolve this?


Environment

  • Model: Dell Studio XPS 13
  • OS: Windows 7 64bit / Ubuntu 12.04 32bit (dual boot)
  • Graphics Driver: Intel HD 3000 (Sandybridge Mobile x86/MMX/SSE2)
  • lshw -C display output:

    *-display               
         description: VGA compatible controller
         product: 2nd Generation Core Processor Family Integrated Graphics Controller
         vendor: Intel Corporation
         physical id: 2
         bus info: pci@0000:00:02.0
         version: 09
         width: 64 bits
         clock: 33MHz
         capabilities: msi pm vga_controller bus_master cap_list rom
         configuration: driver=i915 latency=0
         resources: irq:47 memory:f0000000-f03fffff memory:e0000000-efffffff ioport:2000(size=64)
    
share|improve this question
add comment

1 Answer

up vote 1 down vote accepted

Mario Limonciello was probably the first to alert on this issue, in the #954661 bug report, complaining that:

... At max brightness (what it boots by default) no discernable difference. Then when the screen goes into idle after a few minutes not on AC it starts flickering at me violently. The same thing happens if I manually hit the brightness down keys. The lower the brightness the more aggressive the flicker until I go to zero brightness when the flicker goes away.

Kamal Mostafa from the Canonical Hardware Enablement Team, released an update for the Sputnik Kernel PPA that fixes those issues (probably related to all Intel Graphics based models).

To install it, use the advanced packaging tool via the terminal:

sudo apt-add-repository ppa:canonical-hwe-team/sputnik-kernel
sudo apt-get update
sudo apt-get install linux

Than restart:

sudo shutdown -r now
share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.