This is probably related to the change introduced in Linux 4.1. The Dell keyboard driver can now control various settings about the keyboard back-light and exposes control devices in /sys to change these settings.
Commit: 6cff8d60aa0aba5583ecda09984dbcb2f24cc28d (https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6cff8d60aa0aba5583ecda09984dbcb2f24cc28d)
For some reason the backlight is set to on in certain conditions, ignoring the previous user setting.
This is probably related to the change introduced in Linux 4.1. The Dell keyboard driver can now control various settings about the keyboard back-light and exposes control devices in /sys to change these settings.
Commit: 6cff8d60aa0aba5 583ecda09984dbc b2f24cc28d (https:/ /git.kernel. org/cgit/ linux/kernel/ git/torvalds/ linux.git/ commit/ ?id=6cff8d60aa0 aba5583ecda0998 4dbcb2f24cc28d)
For some reason the backlight is set to on in certain conditions, ignoring the previous user setting.