Red Hat Bugzilla – Bug 758409
Kernel mode set with intel sandy bridge video sets brightness to zero.
Last modified: 2013-08-14 15:43:39 EDT
Created attachment 538179 [details]
Description of problem:
In early boot, when the kernel sets the mode in a intel sandy bridge video adapter the brightness is set to zero. The display then becomes unreadable.
If I disable KMS, the problem disappears.
If I boot in text mode (no X involved) the problem persists as long as KMS is enabled.
Version-Release number of selected component (if applicable):
But I have observed this bug in all F16 kernels.
Steps to Reproduce:
Blank screen, zero brightness
The workaround is to put: echo 7 > /sys/class/backlight/acpi_video0/brightness in some initialization script.
Created attachment 538180 [details]
dmesg with debug on
Do the 3.2.7 or newer kernel updates help this issue?
Bug is still present with kernel-3.2.7-1.fc16.x86_64
kernel-3.3.0-4.fc16 has been pushed to the Fedora 16 stable repository.
Please retest with this update.
I'm typing this with the affected laptop, that still has the bug. If you require more data, please do ask.
Just noticed the [mass update] message. I'm currently running kernel-3.4.9-2.fc16.x86_64 and the bug is still present.
# Mass update to all open bugs.
Kernel 3.6.2-1.fc16 has just been pushed to updates.
This update is a significant rebase from the previous version.
Please retest with this kernel, and let us know if your problem has been fixed.
In the event that you have upgraded to a newer release and the bug you reported
is still present, please change the version field to the newest release you have
encountered the issue with. Before doing so, please ensure you are testing the
latest kernel update in that release and attach any new and relevant information
you may have gathered.
If you are not the original bug reporter and you still experience this bug,
please file a new report, as it is possible that you may be seeing a
(Please don't clone this bug, a fresh bug referencing this bug in the comment is sufficient).
Bug is still present with kernel-3.6.2-1.fc16.x86_64
This message is a reminder that Fedora 16 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 16. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
this bug will be closed as WONTFIX if it remains open with a Fedora
'version' of '16'.
Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version'
to a later Fedora version prior to Fedora 16's end of life.
Bug Reporter: Thank you for reporting this issue and we are sorry that
we may not be able to fix it before Fedora 16 is end of life. If you
would still like to see this bug fixed and are able to reproduce it
against a later version of Fedora, you are encouraged to click on
"Clone This Bug" and open it against that version of Fedora.
Although we aim to fix as many bugs as possible during every release's
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The process we are following is described here:
Fedora 16 changed to end-of-life (EOL) status on 2013-02-12. Fedora 16 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.
If you can reproduce this bug against a currently maintained version of
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Thank you for reporting this bug and we are sorry it could not be fixed.
This bug is alive and well in Fedora 18 with kernel-3.7.9-205.fc18.x86_64. By the way, as the installation processes uses KMS now, the bug shows in the installer, that must be run in basic video mode.
Found the problem and a solution. Apparently it is a BIOS bug where it is claimed the display uses minimum backlight at boot. More info: https://bugzilla.kernel.org/show_bug.cgi?id=21212 and https://bugzilla.kernel.org/show_bug.cgi?id=51141
The solution is to put video.use_bios_initial_backlight=0 in the kernel command line. This can be used right in the installer and should work seamlessly.
A more definitive fix is to add this laptop to a white list of machines needing this parameter. I've made a patch to fix it and have sent it to the ACPI guys, should land in 3.10 I guess: https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=771d09b3c4c45d4d534a83a68e6331b97fd82e15
Still no improvement in Fedora 19 on this issue.
My display controller :
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
Still have to put "xdriver=intel acpi_backlight=vendor" on the boot option line and some value into /sys/class/backlight/intel_backlight/brightness to get an acceptable screen brightness...
Fixed in kernel-3.10.4-100.fc18.x86_64.