diff --git a/sys/compat/linuxkpi/common/include/linux/backlight.h b/sys/compat/linuxkpi/common/include/linux/backlight.h
--- a/sys/compat/linuxkpi/common/include/linux/backlight.h
+++ b/sys/compat/linuxkpi/common/include/linux/backlight.h
@@ -91,6 +91,16 @@
 	bd->props.brightness = bd->ops->get_brightness(bd);
 }
 
+static inline int
+backlight_device_set_brightness(struct backlight_device *bd, int brightness)
+{
+
+	if (brightness > bd->props.max_brightness)
+		return (EINVAL);
+	bd->props.brightness = brightness;
+	return (bd->ops->update_status(bd));
+}
+
 static inline int
 backlight_enable(struct backlight_device *bd)
 {