Public bug reported:
The keyboard backlight is working, and can be controlled by the
BIOS/hardware (Fn+F5 key).
However, it _cannot_ be controlled by either:
- the GUI (power settings), which have no effect, or
- the /sys/devices/platform/dell-laptop/leds/dell::kbd_backlight/ kernel
interface.
Specifically, /sys/devices/platform/dell-
laptop/leds/dell::kbd_backlight/brightness always contains "0",
irrespective of the true state of the hardware (three possible levels:
off, medium, maximum). Writing "1" or "2" to /sys/devices/platform/dell-
laptop/leds/dell::kbd_backlight/brightness as root has no effect.
Interestingly, /sys/devices/platform/dell-
laptop/leds/dell::kbd_backlight/max_brightness reports the correct value
of 2.
Looking at
/sys/devices/platform/dell-laptop/leds/dell::kbd_backlight/brightness_hw_changed
yields:
cat: brightness_hw_changed: No data available
ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: linux-image-5.13.0-28-generic 5.13.0-28.31
ProcVersionSignature: Ubuntu 5.13.0-28.31-generic 5.13.19
Uname: Linux 5.13.0-28-generic x86_64
ApportVersion: 2.20.11-0ubuntu71
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: mbueker 1444 F.... pulseaudio
CasperMD5CheckResult: pass
CurrentDesktop: KDE
Date: Tue Feb 8 14:08:49 2022
InstallationDate: Installed on 2022-01-22 (16 days ago)
InstallationMedia: Kubuntu 21.10 "Impish Indri" - Release amd64 (20211012)
MachineType: Dell Inc. Precision 3551
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.13.0-28-generic
root=/dev/mapper/vgkubuntu-root ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-5.13.0-28-generic N/A
linux-backports-modules-5.13.0-28-generic N/A
linux-firmware 1.201.3
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/10/2021
dmi.bios.release: 1.10
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.10.0
dmi.board.name: 033T3Y
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.10.0:bd12/10/2021:br1.10:svnDellInc.:pnPrecision3551:pvr:rvnDellInc.:rn033T3Y:rvrA00:cvnDellInc.:ct10:cvr:sku09C2:
dmi.product.family: Precision
dmi.product.name: Precision 3551
dmi.product.sku: 09C2
dmi.sys.vendor: Dell Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug impish
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https://bugs.launchpad.net/bugs/1960316
Title:
Dell Precision 3551: keyboard backlight control not working
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