Bug 72976

Summary:	Brightness control becomes binary after suspend on haswell
Product:	xorg	Reporter:	Lionel Landwerlin <lionel.g.landwerlin>
Component:	Driver/intel	Assignee:	Chris Wilson <chris>
Status:	RESOLVED DUPLICATE	QA Contact:	Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Lionel Landwerlin 2013-12-22 19:44:56 UTC

I'm using Linux on my macbook air 2013 (haswell) (using Debian).
After a suspend cycle, the brightness will just go binary, full brightness for the 91-100%, and then completely blank under 91%.

I've noticed the behavior while using Gnome, then tried to reproduce 
by poking at /sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/brightness directly.

Then I tried poking at /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness where the range is 0-2777. And I found the same kind of behavior, except that at the values 2303/2304, the screen would just keep going up/down in brightness without any interection on the /sys interface. Otherwise 2302 and below would be blank and 2305 and above would be full brightness 

It's using the following relevant components :

 xserver-xorg 7.7+4 
 xserver-xorg-video-intel 2.21.15-1+b2
 kernel 3.12.3

I guess the bug is more likely to be somewhere in the kernel than in the X driver.

Folks have reported the bug in other places already :

https://bugzilla.redhat.com/show_bug.cgi?id=989555

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1197482

Comment 1 Jani Nikula 2013-12-30 08:22:35 UTC


*** This bug has been marked as a duplicate of bug 67454 ***

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