FS#44581 - [gnome-session] Xorg custom configuration is ignored

Attached to Project: Arch Linux
Opened by Todo ays (entodoays) - Tuesday, 14 April 2015, 14:37 GMT
Last edited by Jan de Groot (JGC) - Wednesday, 26 October 2016, 14:23 GMT
Task Type Bug Report
Category Packages: Extra
Status Closed
Assigned To Jan de Groot (JGC)
Jan Alexander Steffens (heftig)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:
To be able to control the brightness of my Toshiba laptop after wakeup from sleep I need a custom config file with the following content:

Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"
EndSection

without this, the brightness controls use the "/sys/class/backlight/toshiba" device instead of the "/sys/class/backlight/intel_backlight" which fails to control the actual brightness of the screen after wakeup from sleep.

Until the update to Gnome 3.16, this was working fine. Now, this conf file is not being respected.

Steps to reproduce:
Before sleep:
cat /sys/class/backlight/intel_backlight/actual_brightness
and cat /sys/class/backlight/toshiba/actual_brightness
Values change when changing brightness.
After sleep:
The value of /sys/class/backlight/intel_backlight/actual_brightness does not change when changing brightness but /sys/class/backlight/toshiba/actual_brightness does but the brightness level does not change.

What I tried:
Setting kernel parameters (acpi_backlight=vendor, video.use_native_backlight=1, video.use_native_backlight=0).
The first of these three has no effect. The use of the other two added a third device in /sys/class/backlight called acpi_video0 which has a value identical to "toshiba". Removing these kernel paramaters did not remove the acpi_video0 device.
This task depends upon

Closed by  Jan de Groot (JGC)
Wednesday, 26 October 2016, 14:23 GMT
Reason for closing:  Not a bug
Additional comments about closing:  GNOME doesn't use X backlight configuration anymore.
Comment by Todo ays (entodoays) - Tuesday, 14 April 2015, 14:55 GMT
I tried modifying the .conf file as follows as suggested in a wiki page but without success:
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "Backlight" "intel_backlight" # use your backlight that works here
EndSection
Comment by Andreas Radke (AndyRTR) - Tuesday, 14 April 2015, 16:27 GMT
This is more likely a kernel change related issue introduced with 3.19.x - try the lts kernel to confirm.
Comment by Todo ays (entodoays) - Tuesday, 14 April 2015, 17:14 GMT
I tried the lts kernel already. Should have mentioned it but to no avail. The problem remains. I tried replacing gdm with lightdm and this didn't solve the problem neither.
Comment by Todo ays (entodoays) - Tuesday, 14 April 2015, 20:23 GMT
I noticed the problem with the upgrade to Gnome 3.16. I'm not positively sure that is the culprit but I suspect somehow Gnome is ignoring the .conf file.
Comment by Doug Newgard (Scimmia) - Thursday, 16 April 2015, 03:56 GMT
So does it happen if you use another WM?
Comment by Todo ays (entodoays) - Thursday, 16 April 2015, 07:35 GMT
I installed xfce and I can control brightness before and after sleep. If I log out and start a Gnome session after wakeup from sleep the problem returns. Logging out of Gnome and logging in again in XFCE restores brightness control. This is confirmation that the problem is associated with Gnome 3.16.
Comment by Todo ays (entodoays) - Monday, 20 April 2015, 06:34 GMT
I tried masking the systemd backlight device (sys-devices-LNXSYSTM:00-device:00-TOS6208:00-backlight-toshiba.device), rebooting and testing brightness control but there was no change.

Next I tried masking the systemd service (systemd-backlight@backlight:toshiba.service) hoping Gnome would use the other service (intel_backlight) but again this did not have any effect.
Comment by Todo ays (entodoays) - Tuesday, 21 April 2015, 12:27 GMT
I can change the brightness after sleep only with the following command:

sudo tee /sys/class/backlight/intel_backlight/brightness <<< 700
Comment by Todo ays (entodoays) - Monday, 04 May 2015, 06:30 GMT
Is this problem somehow related to Wayland even though I'm not using Gnome on Wayland?
Comment by Todo ays (entodoays) - Sunday, 10 May 2015, 10:40 GMT
I found out that xbacklight works as well.
Comment by Jan de Groot (JGC) - Wednesday, 26 October 2016, 13:29 GMT
Since gnome 3.16 gnome-settings-daemon uses sysfs to change backlight settings, so X settings are ignored. This has been changed because wayland doesn't provide an interface for backlight control. Instead of having two codepaths there's only one now.

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