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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
commit55944e5e40b1be2afc4855d8d2baf4b73d1876b5 (patch)
tree33f869f55a1b149e9b7c2b7e201867ca5dd52992 /man/systemd-backlight@.service.xml
parentInitial commit. (diff)
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systemd-55944e5e40b1be2afc4855d8d2baf4b73d1876b5.zip
Adding upstream version 255.4.upstream/255.4
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version="1.0"?>
+<!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+<refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'
+ xmlns:xi="http://www.w3.org/2001/XInclude">
+
+ <refentryinfo>
+ <title>systemd-backlight@.service</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-backlight@.service</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-backlight@.service</refname>
+ <refname>systemd-backlight</refname>
+ <refpurpose>Load and save the display backlight brightness at boot and shutdown</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>systemd-backlight@.service</filename></para>
+ <para><filename>/usr/lib/systemd/systemd-backlight</filename> save [backlight|leds]:DEVICE</para>
+ <para><filename>/usr/lib/systemd/systemd-backlight</filename> load [backlight|leds]:DEVICE</para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-backlight@.service</filename> is a service that restores the display backlight
+ brightness at early boot and saves it at shutdown. On disk, the backlight brightness is stored in
+ <filename>/var/lib/systemd/backlight/</filename>. During loading, if the udev property
+ <option>ID_BACKLIGHT_CLAMP</option> is not set to false, the brightness is clamped to a value of at least
+ 1 or 5% of maximum brightness, whichever is greater. The percentage can be adjusted by specifying a
+ percentage (needs to be suffixed with <literal>%</literal>, e.g. <literal>30%</literal>) to the property
+ <option>ID_BACKLIGHT_CLAMP</option>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Kernel Command Line</title>
+
+ <para><filename>systemd-backlight</filename> understands the
+ following kernel command line parameter:</para>
+
+ <variablelist class='kernel-commandline-options'>
+ <varlistentry>
+ <term><varname>systemd.restore_state=</varname></term>
+
+ <listitem><para>Takes a boolean argument. Defaults to
+ <literal>1</literal>. If <literal>0</literal>, does not
+ restore the backlight settings on boot. However, settings will
+ still be stored on shutdown. </para>
+
+ <xi:include href="version-info.xml" xpointer="v209"/></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>