Red Hat Bugzilla – Bug 834910
Screen backlight not functioning after kernel update
Last modified: 2012-07-09 04:49:59 EDT
Description of problem:
When booting recent kernels (>= 3.4.0) my laptop's screen remains black, the backlight shuts down as soon as the initram image is loaded. No plymouth, no login manager, nothing. Hard drive activity is ordinary and SysReq keys and Alt-Ctrl-Del work, so the O.S. is properly launched even though nothing is visibly displayed.
Version-Release number of selected component (if applicable):
Fedora 17, normal update channels.
Steps to Reproduce:
1. Yum update, install newer kernel.
3. Enjoy the void.
Might be related to other issues such as #752727 or #707688. Except that passing acpi_backlight=vendor or any other boot option doesn't help.
Additionally, my laptop is a Sony VAIO VPC CW1S1E whose screen has been known to be partially unsupported by GNU/Linux (EDID number wrongly recognized). That being said, I had (and still have) no problem booting with kernel 3.3.7, and even backlight-adjustment functions work.
I believe this is a regression in the ACPI layer. Can you attach the output of acpidump?
Created attachment 594274 [details]
OK, this does indeed look like the kernel.org bug I linked to. Your machine's ACPI lacks _DOS.
I'll try to get a fix committed today.
Please try this scratch build kernel when it completes:
I tested it several times, and it appears to work. Thanks!
Thanks for testing. Fixed in Fedora git.
kernel-3.4.4-5.fc17 has been submitted as an update for Fedora 17.
kernel-3.4.4-4.fc16 has been submitted as an update for Fedora 16.
* should fix your issue,
* was pushed to the Fedora 16 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing kernel-3.4.4-4.fc16'
as soon as you are able to, then reboot.
Please go to the following url:
then log in and leave karma (feedback).
kernel-3.4.4-5.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.
kernel-3.4.4-4.fc16 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.
*** Bug 830292 has been marked as a duplicate of this bug. ***