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[Bug 1040718] New: Backlight Control Lost with Install of NVidia Driver on 42.2, fix for 42.3?
  • From: bugzilla_noreply@xxxxxxxxxx
  • Date: Thu, 25 May 2017 01:01:19 +0000
  • Message-id: <>

Bug ID: 1040718
Summary: Backlight Control Lost with Install of NVidia Driver
on 42.2, fix for 42.3?
Classification: openSUSE
Product: openSUSE Distribution
Version: Leap 42.2
Hardware: Other
OS: Other
Status: NEW
Severity: Normal
Priority: P5 - None
Component: X.Org
Assignee: xorg-maintainer-bugs@xxxxxxxxxxxxxxxxxxxxxx
Reporter: drankinatty@xxxxxxxxxxxxxxxxxx
QA Contact: xorg-maintainer-bugs@xxxxxxxxxxxxxxxxxxxxxx
Found By: ---
Blocker: ---

Created attachment 726331
lspci -v output


HP-8760w Elitebook Pro,
Intel i7-2620M CPU @ 2.70GHz
NVIDIA GF104GLM [Quadro 3000M]

OS: Leap 42.2

Backlight control is lost in sysfs on install of NVidia driver (nouveau
provides nv_backlight interface). This is being filed here on suggestion from
the Factory mailing list, but may need to go to or

This is a problem that has plagued my HP8760w laptop (with NVidia Quadro
3000M) since installing Leap 42.2. When using the Nouveau driver, backlight
control is provided via:

/sys/class/backlight/acpi_video0 (the standard interface), and


Within each of the backlight control directories, you have various parameters
that allow you to obtain the maximum brightness value (max_brightness) to allow
proper scaling of change requests and the (brightness) control interface
allowing you to set the display brightness with values (0 - max_brightness).

The problem is that most display interfaces (including laptop control keys)
change the values within the acpi_video0 interface (0-20 scale), so for nouveau
you end up having to set an inotiifywait watch on acpi_video0 and then update
nv_backlight (0-100 scale) with changes.

This works fine for nouveau. However, when the NVidia drivers are installed,
the nv_backlight interface is removed from the system leaving only acpi_video0.
acpi_video0 has no interface to display brightness itself.

With Arch running on the same box, there is a kernel module (actually a
couple of packages for it in AUR -- equivalent to buildservice/home packages)
that provides the nvidia_backlight interface where backlight can be controlled
in the same manner as with the nouveau interface. E.g.

It is critical that there be some manner of backlight control provided when
using the NVidia driver. While FW5/Gnome may provide hooks, for every other
desktop the display brightness is stuck on HIGH with no way to turn it down or
control the 'power' for the display backlight. xrandr does not adjust the
display backlight. It adjusts the color brightness, which while it may have the
same visible effect may have negative effects on battery life and component
wear compared to proper backlight adjustment.

Is there any way to address this for upcoming Leap 42.3? Can openSuSE provide
a kernel module interface for backlight control with NVidia similar to what is
done by the Arch AUR packages? (they continue to work with Linux 4.10, so there
should be kernel compatibility without much, if any, patching required)

Let me know if there is any other hardware information you need and I'm happy
to provide it.

I'll attach the 'lspci -v' output as starters.

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