X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsystemd-backlight%40.service.xml;h=a259f5d583cd79d05af03ae34e6314fdd95ee9ab;hb=757b23a6cd15f4b5fdcc3ea99754b7173aff0309;hp=2b73625e91ae19bf7c1358521bbb92354b8fb6d5;hpb=6b4991cfde6c0a0b62e836ca75ae362779c474d4;p=elogind.git

diff --git a/man/systemd-backlight@.service.xml b/man/systemd-backlight@.service.xml
index 2b73625e9..a259f5d58 100644
--- a/man/systemd-backlight@.service.xml
+++ b/man/systemd-backlight@.service.xml
@@ -21,53 +21,74 @@
 -->
 <refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'>
 
-        <refentryinfo>
-                <title>systemd-backlight@.service</title>
-                <productname>systemd</productname>
-
-                <authorgroup>
-                        <author>
-                                <contrib>Developer</contrib>
-                                <firstname>Lennart</firstname>
-                                <surname>Poettering</surname>
-                                <email>lennart@poettering.net</email>
-                        </author>
-                </authorgroup>
-        </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></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/backlight/</filename>. Note that by
-                default, only firmware backlight devices are
-                saved/restored.</para>
-        </refsect1>
-
-        <refsect1>
-                <title>See Also</title>
-                <para>
-                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-                </para>
-        </refsect1>
+  <refentryinfo>
+    <title>systemd-backlight@.service</title>
+    <productname>systemd</productname>
+
+    <authorgroup>
+      <author>
+        <contrib>Developer</contrib>
+        <firstname>Lennart</firstname>
+        <surname>Poettering</surname>
+        <email>lennart@poettering.net</email>
+      </author>
+    </authorgroup>
+  </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></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 udev property <option>ID_BACKLIGHT_CLAMP</option> is
+    not set to false value, the brightness is clamped to a value of at
+    least 1 or 5% of maximum brightness, whichever is greater. This
+    restriction will be removed when the kernel allows user space to
+    reliably set a brightness value which does not turn off the
+    display.</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></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>See Also</title>
+    <para>
+      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+    </para>
+  </refsect1>
 
 </refentry>