Arch Linux

kakawait

Member

Registered: 2020-04-15

Posts: 2

Lenovo t480s keyboard backlight not restored after reboot

Hi,

I'm using Arch on Lenovo T480s that is shipped with keyboard that we can light.

Keyboard backlight works great, but each time I reboot (only reboot, see Edit2) is not restored and always off.
Even more strange that I though following systemd services might be responsible to reload latest setting

archi% systemctl | grep tpacpi
  sys-devices-platform-thinkpad_acpi-leds-tpacpi::kbd_backlight.device                                  loaded active plugged   /sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight

  systemd-backlight@leds:tpacpi::kbd_backlight.service                                                  loaded active exited    Load/Save Screen Backlight Brightness of leds:tpacpi::kbd_backlight

I checked dmesg

archi% dmesg | grep think
[   16.412851] thinkpad_acpi: ThinkPad ACPI Extras v0.26
[   16.412852] thinkpad_acpi: [url]http://ibm-acpi.sf.net/[/url]
[   16.412853] thinkpad_acpi: ThinkPad BIOS N22ET59W (1.36 ), EC N22HT33W
[   16.412854] thinkpad_acpi: Lenovo ThinkPad T480s, model 20L8S6K800
[   16.413351] thinkpad_acpi: radio switch found; radios are enabled
[   16.413627] thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
[   16.413628] thinkpad_acpi: Disabling thinkpad-acpi brightness events by default...
[   16.416081] thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked
[   16.417043] thinkpad_acpi: rfkill switch tpacpi_wwan_sw: radio is unblocked
[   16.425237] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one
[   16.430454] thinkpad_acpi: battery 1 registered (start 0, stop 100)
[   16.430533] input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input22

and journalctl

Apr 15 21:58:07 archi systemd[1]: Stopping Load/Save Screen Backlight Brightness of backlight:intel_backlight...
Apr 15 21:58:07 archi systemd[1]: Stopping Load/Save Screen Backlight Brightness of leds:tpacpi::kbd_backlight...
Apr 15 21:58:07 archi systemd[1]: systemd-backlight@backlight:intel_backlight.service: Succeeded.
Apr 15 21:58:07 archi systemd[1]: Stopped Load/Save Screen Backlight Brightness of backlight:intel_backlight.
Apr 15 21:58:07 archi audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-backlight@backlight:intel_backlight comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Apr 15 21:58:07 archi systemd[1]: systemd-backlight@leds:tpacpi::kbd_backlight.service: Succeeded.
Apr 15 21:58:07 archi systemd[1]: Stopped Load/Save Screen Backlight Brightness of leds:tpacpi::kbd_backlight.
Apr 15 21:58:07 archi audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-backlight@leds:tpacpi::kbd_backlight comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Apr 15 21:58:07 archi systemd[1]: Removed slice system-systemd\x2dbacklight.slice.
Apr 15 21:58:42 archi kernel: thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
Apr 15 21:58:42 archi kernel: thinkpad_acpi: Standard ACPI backlight interface available, not loading native one
Apr 15 21:58:42 archi systemd[1]: Created slice system-systemd\x2dbacklight.slice.
Apr 15 21:58:42 archi systemd[1]: Starting Load/Save Screen Backlight Brightness of leds:tpacpi::kbd_backlight...
Apr 15 21:58:42 archi systemd[1]: Finished Load/Save Screen Backlight Brightness of leds:tpacpi::kbd_backlight.
Apr 15 21:58:42 archi audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-backlight@leds:tpacpi::kbd_backlight comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Apr 15 21:58:44 archi systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:intel_backlight...
Apr 15 21:58:44 archi systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:intel_backlight.
Apr 15 21:58:44 archi audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-backlight@backlight:intel_backlight comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'

but nothing seems to be wrong.

Any idea?

-------

Edit: Strange thing, when I checked

archi% cat /var/lib/systemd/backlight/platform-thinkpad_acpi:leds:tpacpi::kbd_backlight
2
archi% cat /sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/brightness
2

Value is correct (2 means bright) but keyboard light is off... Maybe not related to Arch itself?

And other thing that confirm value is correct is when I FN+Space (to start backlight) is on and turning off immediatly. I have to replay FN+Space to getting work

Edit2: After some tests I saw that bug only appears on reboot

• systemctl poweroff OK (no problem)

• systemctl reboot KO (kb backlight bug)

• systemctl hibernate OK (no problem)

• systemctl suspend OK (no problem)

Thank you for time you could spend to help me

Last edited by kakawait (2020-04-18 12:19:04)