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Federico Di Pierro edited this page Mar 9, 2024 · 40 revisions

Table of contents

  1. Common issues
  2. Dbus tricks

Common Issues

This is a list of the most commonly asked questions.

Where is Clight log?

Since Clight 4.9, log file is located under $XDG_RUNTIME_DIR/clight/clight.log, that should resolve to /run/user/$uid/clight/clight.log.
It is a tmpfs path, therefore the log file will be lost after a reboot.
If XDG_RUNTIME_DIR is not set, Clight will fallback at trying old XDG_DATA_HOME path, ie: into $XDG_DATA_HOME/clight/clight.log; normally it should resolve to .local/share/clight/clight.log.

Where is Clight conf?

Since Clight 4.10, its config is located at /etc/clight/clight.conf and each module config is located under /etc/clight/modules.conf.d/ folder.
In older versions, Clight conf file was located in /etc/default/clight.conf.
For more info: https://github.com/FedeDP/Clight/wiki/Config and man clight.

How to enable verbose mode?

Open Clight conf file and uncomment verbose = true; line.

Clight does not detect my external monitor

Check that [Clightd](https://github.com/FedeDP/Clightd/wiki/Ddcutil] was built with ddcutil support; moreover, check that your monitor actually supports DDC/CI: sudo ddcutil detect.

Does Clight support monitor hotplug?

Yes, since Clight 4.8.
Clight relies upon Clightd (>=5.5) that polls 'drm' udev subsystem and on any event, it reloads the list of external monitors.
As soon as a new monitor is detected, Clight will gracefully set current backlight percentage on it as well as refresh gamma temperature.
For more info: https://github.com/FedeDP/Clightd/wiki/Ddcutil#monitor-hotplug.

Clight keeps running even after my session was killed

Some distro ship a systemd-logind conf (/etc/systemd/logind.conf) with flag KillUserProcesses=no.
This means clight will not get killed upon user leaving the session, and will not properly get killed on system shutdown.
I encourage to set the flag to yes.
For more info, read here: https://fedoraproject.org/wiki/Changes/KillUserProcesses_by_default.
You can check your system current KillUserProcesses value through dbus:
busctl get-property org.freedesktop.login1 /org/freedesktop/login1 org.freedesktop.login1.Manager KillUserProcesses

Clight on wayland

Unfortunately on Wayland there is yet no standard protocol for gamma, dpms and screenshots handling.
Most probably your DE does not implement specific protocols.
For more info: https://github.com/FedeDP/Clight/wiki/Modules#wayland-support.

Geoclue asks for permission

Please try to append following lines to /etc/geoclue/geoclue.conf:

[clightc]
allowed=true
system=false
users=

If issues persist, please fill a bug report.

Screen temperature is resetted when backlight changes

Disable colord daemon: https://github.com/FedeDP/Clight/issues/236#issuecomment-960138088

Clight sets 0 backlight level, but my screen turns black!

Some monitors handle the 0 backlight level as "switched off"; in these cases, you can just update Clight sensor.conf config file, changing the backlight curves starting points from 0.0 to an higher backlight level, like 0.1, eg:

sensor:
{
    ac_regression_points = [ 0.1, 0.15, 0.29, 0.45, 0.61, 0.74, 0.81, 0.88, 0.93, 0.97, 1.0 ];
    batt_regression_points = [ 0.1, 0.15, 0.23, 0.36, 0.52, 0.59, 0.65, 0.71, 0.75, 0.78, 0.80 ];

How to uninstall it?

If you manually run sudo make install to install Clight, you might be surprised that there is no uninstall target.
This is a CMake issue; to workaround it, you can follow: https://stackoverflow.com/questions/41471620/cmake-support-make-uninstall.

DBus tricks

Clight may work well on its own, but where it shines is its DBus interface! You can control many aspects of how the program works through integration with other programs or your own scripts!

How do I pause the dimmer temporarily?

Clight implements the Freedesktop ScreenSaver interface, meaning many programs will automatically cause Clight to pause itself. If you want finer control, you can use Clight's dbus interface:

busctl busctl --user call org.clight.clight /org/clight/clight org.clight.clight Inhibit b true

and likewise, you can use false to return the dimmer to normal. You can write a script to toggle inhibition:

#!/usr/bin/env python3
import dbus

bus = dbus.SessionBus()
prop = bus.get_object('org.clight.clight','/org/clight/clight')
currVal = prop.Get('org.clight.clight','Inhibited',dbus_interface='org.freedesktop.DBus.Properties')
prop.Inhibit(not currVal,dbus_interface='org.clight.clight')

Finally, Clight desktop file has a quick action to pause/resume dimmer.

How do I change the backlight manually?

Clight should automatically control your brightness to acceptable values, but if you want to override it manually, there are two ways:

  1. Use IncBl and DecBl to increase/decrease.

These two dbus methods can be used to increase and decrease the backlight by a certain percentage.

busctl --user call org.clight.clight /org/clight/clight org.clight.clight IncBl d 0.1

will increase the backlight by 10%. Likewise, you can use DecBl to decrease by 10%.

Here is another script to change the backlight:

#!/usr/bin/env python3

import dbus
import sys

bus = dbus.SessionBus()
obj = bus.get_object('org.clight.clight','/org/clight/clight')

if sys.argv[1] == '-inc':
	obj.IncBl(float(sys.argv[2]),dbus_interface='org.clight.clight')
if sys.argv[1] == '-dec':
	obj.DecBl(float(sys.argv[2]),dbus_interface='org.clight.clight')

which can be used like backlight -inc 0.1 or backlight -dec 0.1.

  1. Set the backlight directly.

The DBus property BlPct can be used to set the backlight to a specific value.

busctl call org.clightd.clightd /org/clightd/clightd/Backlight org.clightd.clightd.Backlight SetAll d\(bdu\)s 0.5 false 0 0 ""

where 0.5 can be changed to the desired value.

Stop Clight calibrating backlight

You can use the following DBus call to disable automatic screen backlight calibration:

busctl --user set-property org.clight.clight /org/clight/clight/Conf/Backlight org.clight.clight.Conf.Backlight NoAutoCalib b true

Use false to enable it back.
This can again be put in a script to toggle whenever you need to:

#!/usr/bin/env python3
import dbus

bus = dbus.SessionBus()
prop = bus.get_object('org.clight.clight','/org/clight/clight/Conf/Backlight')
currVal = prop.Get('org.clight.clight.Conf.Backlight','NoAutoCalib',dbus_interface='org.freedesktop.DBus.Properties')
prop.Set('org.clight.clight.Conf.Backlight','NoAutoCalib',not currVal,dbus_interface='org.freedesktop.DBus.Properties')

Finally, Clight desktop file has a quick action to pause/resume backlight autocalibration.

I want to set 100% backlight when opening vlc to watch a movie

Sure, it is as simple as creating a video player launcher script and adding:

busctl --user set-property org.clight.clight /org/clight/clight/Conf/Backlight org.clight.clight.Conf.Backlight NoAutoCalib "b" true
busctl --user call org.clight.clight /org/clight/clight org.clight.clight IncBl "d" 1.0

before video player command, and then:

busctl --user set-property org.clight.clight /org/clight/clight/Conf/Backlight org.clight.clight.Conf.Backlight NoAutoCalib "b" false

after it, to enable back automatic screen backlight calibration.

DE Night Theme

Again, this is super easy using Clight dbus API.
Please, head to https://github.com/FedeDP/Clight/wiki/DE-Night-Mode-scripts for a list of scripts for various DEs.

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