diff options
| -rw-r--r-- | man/systemd-backlight@.service.xml | 9 | ||||
| -rw-r--r-- | src/backlight/backlight.c | 5 |
2 files changed, 12 insertions, 2 deletions
diff --git a/man/systemd-backlight@.service.xml b/man/systemd-backlight@.service.xml index 453afbf1b4..21c6437efa 100644 --- 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> diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c index 1271a66983..c79ad6520c 100644 --- a/src/backlight/backlight.c +++ b/src/backlight/backlight.c @@ -373,6 +373,7 @@ int main(int argc, char *argv[]) { if (streq(argv[1], "load")) { _cleanup_free_ char *value = NULL; + const char *clamp; if (!shall_restore_state()) return EXIT_SUCCESS; @@ -390,7 +391,9 @@ int main(int argc, char *argv[]) { return EXIT_FAILURE; } - clamp_brightness(device, &value, max_brightness); + clamp = udev_device_get_property_value(device, "ID_BACKLIGHT_CLAMP"); + if (!clamp || parse_boolean(clamp) != 0) /* default to clamping */ + clamp_brightness(device, &value, max_brightness); r = udev_device_set_sysattr_value(device, "brightness", value); if (r < 0) { |