Comment 0 for bug 1693126

Two issues here:
1. No sysfs "/sys/devices/platform/dell-laptop/leds/dell::kbd_backlight"
The patch fixes the issue:
commit 8d2c4538dbc7154c4aed1364db127a0e51dbd459
Author: Alex Hung <email address hidden>
Date: Thu Feb 16 20:58:03 2017 +0800

    platform/x86: dell-laptop: Add Latitude 7480 and others to the DMI whitelist

2. The sysfs exits, but backlight cannot be controlled by "brightness" attribute.
The patch fixes the issue:
commit 9216e0dcb5533a999d544d0af8661118e0588e1d
Author: Pali Rohár <email address hidden>
Date: Sun Apr 23 21:40:47 2017 +0200

    platform/x86: dell-laptop: Add keyboard backlight timeout AC settings