backlight flickers with Intel HD Graphics 4400 and 3.13.0-44

[Stephen Gildea]

Since upgrading my Trusty kernel to 3.13.0-44.73, the backlight on my Ultrabook laptop flickers frequently. It seems to flicker whenever an X application refreshes part of its window. The backlight flicker is most noticeable with Chrome browser and mplayer video player. Sometimes it will flicker a few times, sometimes continue to flicker quickly. Occasionally the backlight will stay off for a while, and then I can see the windows very faintly if I have good room lighting, so it's definitely a backlight problem.

My display hardware is Intel HD Graphics 4400 (i965 driver)

I backed off to the previous kernel, 3.13.0-43.72, and the flickering problem stopped. Now backlight stays on consistently, as it should.

[Stephen Gildea (stepheng+launchpad)]

I now believe this problem to be hardware flakiness, since it happens only when my Sony VAIO Pro 13 has been playing movies for a few hours, and I have reproduced it with the -43 kernel, too.
If nobody else sees this, we can close this bug report.

[penalvch (penalvch)]

Stephen Gildea, thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command only once, as it will automatically gather debugging information, in a terminal:
apport-collect 1414101

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Launchpad Janitor (janitor)]

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