Red Hat Bugzilla – Bug 748210
Kernel panic when turning off screen backlight using laptop Fn key
Last modified: 2011-12-23 03:03:20 EST
Description of problem:
Since I installed Fedora 16 I'm not able to turn off the screen backlight using the Fn key. It is a Lenovo Ideapad Y450-PEI. When I press Fn + F2 (key to toggle screen backlight), my screen is black and I'm not able to get it back. I managed to get a strong light and see things like stack trace on my screen and something like "Kernel is unable to handle ......"
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Press Fn + F2 to turn off screen backlight
2. Press Fn + F2 again to turn it on
The screen backlight isn't on and something is printed on the screen.
The screen backlight is on and nothing is affected
If possible, please don't let me try to read the screen when error occurs. It's so hard to do so...
I'm using the nouveau driver with a nVIDIA GT130M card. Haven't tried if proprietary driver will solve the problem.
Can you take a picture of the screen? We need the backtrace to really get started here.
(In reply to comment #2)
> Can you take a picture of the screen? We need the backtrace to really get
> started here.
I'm sorry, when I press Fn + F2 the screen backlight turns off immediately so I can't see anything unless I use a torch... and it seems that the length of the backtrace exceeded the height of the screen...
I'll try my best to put them down. I'll reply later here.
The same problem with Lenovo Ideapad S205 when I switch off/on backlight. The result is kernel oops and nothing in /var/log/messages, the version of kernel is 3.1.0-1.fc16.x86_64.
I suspect, that the culprit is the ideapad-laptop module, see the attached pictures of the screen.
Created attachment 530403 [details]
The kernel oops - the first screen.
Created attachment 530405 [details]
The kernel oops - the second screen.
My HW profile:
(In reply to comment #6)
> Created attachment 530405 [details]
> The kernel oops - the second screen.
Oh thank you very much for these pictures. My screen turns off after Fn + F2 so I can't see anything.
Using Fn to toggle screen backlight is working very well in my Archlinux with the latest kernel, installed on the same machine.
I have read somewhere that the problem does not occur on ubuntu 32-bit. It does however on Ubuntu 64-bit, I confirm. So - has anybody tried this with a 32-bit Fedora installation?
I've updated my Archlinux to the latest kernel 3.1.0-2 and the problem can now be reproduced on Arch.
It is an upstream problem and the patch is available.
Proposing as NTH for F16: system crasher, will be present in live images hence can't be entirely fixed with an update.
Fedora Bugzappers volunteer triage team
This when upstream in 3.2 as commit d4afc7754a60b885b63ef23fd194984e2d53a4e6. I'll bring it back to f16.
The patch was added. It will be in the next kernel build.
*** Bug 746016 has been marked as a duplicate of this bug. ***
*** Bug 745568 has been marked as a duplicate of this bug. ***