Bug 473567 - MacBook brightness flickers at login screen and while setting brightness level
MacBook brightness flickers at login screen and while setting brightness level
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Kernel Maintainer List
Fedora Extras Quality Assurance
Depends On:
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Reported: 2008-11-29 06:54 EST by Roman
Modified: 2009-11-25 07:22 EST (History)
2 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2009-11-25 07:22:38 EST
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RHEL 7.3 requirements from Atomic Host:
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External Trackers
Tracker ID Priority Status Summary Last Updated
Linux Kernel 11769 None None None Never

  None (edit)
Description Roman 2008-11-29 06:54:00 EST
While booting the display brightness is set to the last brightness I had when shutting down the laptop. (Till here it's all right.)

But, when the login screen appears, the brightness flickers heavily for about 1-2 sec. and remains at the highest brightness level. (This is very uncool, because the high brightness level will drain the battery more than necessary and IMHO the flickering will not be good for the hardware either.)

As the brightness remains at the highest brightness level after booting I triggered the brightness with the brightness buttons. But the brightness steps might be faulty or invalid because the display brightness flickers again and jumps from highest to lowest level back and forth e.g. ~7% brightness is nearly a 100%, ~10% is 0%. And sometimes the buttons seems to be changed because I had to press the button to increase brightness for lowering the brightness and vice versa.

I also tried to trigger the brightness via "Power Management" settings in GNOME and as described before the display brightness flickers while setting a default value and after staying inactive for round about 10 sec. the screen flickers again and drops to the max. or min. brightness level. (This might depend on the faulty brightness steps.)

The display flickers while switching the power management profile by un-/plugging the power cable.

My Hardware:
MacBook 13" rev. 1.1, Intel GMA950

Steps to Reproduce:
1. boot till login screen appears (flickering comes automatically)
2. setting brightness level via keyboard buttons
3. setting default brightness level via GNOME's Power Management
4. changing the power management profile by un-/plugging the power cable

Actual results:
The display brightness flickers in all of the four steps above and could not be set accurately.

Expected results:
First, setting the brightness levels without flickering (correct brightness steps).
Second, retaining the last display brightness level at boot time.

Additional info:
I searched a bit for similar problems but I couldn't find a solution yet. The best hit I got was at the linux kernel bugtracker #11769 (added as external bug) which even relates to the brightness reset on boot time.
Comment 1 Fabian Deutsch 2008-12-02 07:01:09 EST
I've got the same MacBook and it seems to be a regression to F9.
Screen-Flickers didn't appear in F9 with all updates.
Comment 2 Bug Zapper 2009-11-18 04:04:10 EST
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Comment 3 Fabian Deutsch 2009-11-25 07:22:38 EST
Seems to be fixed in F12.

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