I am working in Dell. I have some digging on this issue. There are two symptoms reported in the thread – the keyboard backlight unexpectedly turns ON on boot and after the resume from a screen lock. These are due to two different causes.
- the backlight unexpectedly turns ON on boot, regardless of the previous state of brightness. This is an intentional behavior of “unity- settings-daemon”. This daemon reads the brightness value of kbd_backlight (via “upowerd”) when system starts up, and turn it on (via upowerd) if the read value is 0 (which indicates the backlight is off). Even worse, the daemon does not make this behavior configurable. - The backlight unexpectedly turns ON after the resume from a screen lock, regardless of the previous state of brightness. The “unity- settings-daemon” also deals with power management things. It turns the backlight off when the system is about to dim screen for power saving reason. Also, the daemon thought itself as the only S/W piece that can set the brightness of backlight and no other ones will change it, so it does not query for the current state of backlight before dimming it. But the fact is, Dell’s BIOS already dimmed the backlight due to a timeout of idle. When screen resumes, the daemon resumes the backlight to ON as it assumed the backlight was ON before dim. The issue should start happening since the introduce of commit 6cff8d60aa0aba5583ecda09984dbcb2f24cc28d (pointed out in #5), because it implements a new “kbd_backlight” driver in dell-laptop kernel module. It it gives the chance to “upowerd” for having the control over the keyboard backlight hardware on Dell laptops. The workaround provided in #47 does work because it denies “unity- settings-daemon” from sending DBUS commands that regarding kbd_backlight set/get to upowerd. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1510344 Title: Keyboard Backlight Turns on at boot Status in Dell Sputnik: Confirmed Status in One Hundred Papercuts: Confirmed Status in Linux: New Status in linux package in Ubuntu: Triaged Bug description: System: Dell XPS 13 9343 Action: Boot computer Expected Behavior: Keyboard backlight would be off when computer is booted Actual Behavior: Keyboard backlight is on at boot This did not happen with Ubuntu 15.04 There are new files in Ubuntu 15.10 - /sys/class/leds/dell::kbd_backlight$ cat stop_timeout 60s cat start_triggers +keyboard +touchpad cat trigger [none] AC-online BAT0-charging-or-full BAT0-charging BAT0-full BAT0-charging-blink-full-solid usb-gadget usb-host cpu0 cpu1 cpu2 cpu3 mmc0 rfkill0 cat brightness 2 --- Unsure if these files are important, but included in the report ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: linux-image-4.1.0-2-generic 4.1.0-2.2 ProcVersionSignature: Ubuntu 4.1.0-2.2-generic 4.1.3 Uname: Linux 4.1.0-2-generic x86_64 ApportVersion: 2.18-0ubuntu5 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: ubuntu 2488 F.... pulseaudio /dev/snd/controlC0: ubuntu 2488 F.... pulseaudio CasperVersion: 1.362 CurrentDesktop: Unity Date: Tue Oct 27 01:29:47 2015 IwConfig: enx00249b0981e3 no wireless extensions. lo no wireless extensions. LiveMediaBuild: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150730) MachineType: Dell Inc. XPS 13 9343 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/username.seed boot=casper quiet splash --- cdrom-detect/try-usb=true noprompt RelatedPackageVersions: linux-restricted-modules-4.1.0-2-generic N/A linux-backports-modules-4.1.0-2-generic N/A linux-firmware 1.145 RfKill: 0: hci0: Bluetooth Soft blocked: no Hard blocked: no SourcePackage: linux UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 07/14/2015 dmi.bios.vendor: Dell Inc. dmi.bios.version: A05 dmi.board.name: 0TM99H dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA05:bd07/14/2015:svnDellInc.:pnXPS139343:pvr:rvnDellInc.:rn0TM99H:rvrA00:cvnDellInc.:ct9:cvr: dmi.product.name: XPS 13 9343 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/dell-sputnik/+bug/1510344/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp