backlight: let udev properties override clamping

[elogind.git] / man / systemd-backlight@.service.xml

diff --git a/man/systemd-backlight@.service.xml b/man/systemd-backlight@.service.xml
index 453afbf1b415ec4985da80e0a44d8931b08caf90..21c6437efab4d277a800cd6dea607c5703ffaeb0 100644 (file)
--- a/man/systemd-backlight@.service.xml
+++ b/man/systemd-backlight@.service.xml
@@ -58,7 +58,14 @@
                 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>.</para>
+                <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>