Screen Backlight Error [SOLVED]

Caeruleas · 2018-05-12 05:45:42

Hi, whenever I boot up my laptop I always see this error:

[FAILED] Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.
See 'systemctl status systemd-backlight@backlight:acpi_video0.service' for details.

But then right after it says:

[ OK ] Started Load/Save Screen Backlight Brightness of backlight:radeon_bl0.

I ran the systemctl command above and this came up:

● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
   Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sat 2018-05-12 17:32:53 NZST; 6min ago
     Docs: man:systemd-backlight@.service(8)
  Process: 342 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=1/FAILURE)
 Main PID: 342 (code=exited, status=1/FAILURE)

May 12 17:32:53 Caeruleas systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
May 12 17:32:53 Caeruleas systemd[1]: systemd-backlight@backlight:acpi_video0.service: Main process exited, code=exited, status=1/FAILURE
May 12 17:32:53 Caeruleas systemd[1]: systemd-backlight@backlight:acpi_video0.service: Failed with result 'exit-code'.
May 12 17:32:53 Caeruleas systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.

After a search on google, I ran these commands:

cd /sys/class/backlight
ls

and the only file in there is radeon_bl0.

I have had this error show the whole time I have had Arch Linux, and it doesn't seem to affect my every-day use, but I don't know a lot about this and I would like this to be fixed so that I won't have to worry about it at all.

Last edited by Caeruleas (2018-05-12 22:20:47)

jasonwryan · 2018-05-12 06:44:19

Paste the output of `systemctl list-unit-files --state=enabled`

seth · 2018-05-12 07:01:11

So why is the service enabled for this device itfp? Just disable it.

Caeruleas · 2018-05-12 21:44:23

jasonwryan wrote:

Paste the output of `systemctl list-unit-files --state=enabled`

UNIT FILE                                   STATE  
acpid.service                               enabled
autovt@.service                             enabled
dbus-fi.w1.wpa_supplicant1.service          enabled
dbus-org.freedesktop.NetworkManager.service enabled
dbus-org.freedesktop.nm-dispatcher.service  enabled
display-manager.service                     enabled
getty@.service                              enabled
NetworkManager-dispatcher.service           enabled
NetworkManager.service                      enabled
plexmediaserver.service                     enabled
sddm.service                                enabled
systemd-timesyncd.service                   enabled
wpa_supplicant.service                      enabled
remote-fs.target                            enabled

14 unit files listed.

seth wrote:

So why is the service enabled for this device itfp? Just disable it.

I tried running

sudo systemctl disable systemd-backlight@backlight:acpi_video0

and then restarted but the error still shows. Unless you wanted me to disable something else?

jasonwryan · 2018-05-12 21:49:02

So did you disable the service before posting the output of `systemctl list-unit-files`?

If it is still appearing, you can mask the service.

Caeruleas · 2018-05-12 22:00:33

jasonwryan wrote:

So did you disable the service before posting the output of `systemctl list-unit-files`?
If it is still appearing, you can mask the service.

No I only tried to disable it after I posted the output. Just out of curiosity I tried to enable it again but it outputs:

The unit files have no installation config (WantedBy, RequiredBy, Also, Alias
settings in the [Install] section, and DefaultInstance for template units).
This means they are not meant to be enabled using systemctl.
Possible reasons for having this kind of units are:
1) A unit may be statically enabled by being symlinked from another unit's
   .wants/ or .requires/ directory.
2) A unit's purpose may be to act as a helper for some other unit which has
   a requirement dependency on it.
3) A unit may be started when needed via activation (socket, path, timer,
   D-Bus, udev, scripted systemctl call, ...).
4) In case of template units, the unit is meant to be enabled with some
   instance name specified.

And how do you mask a service? I am still new to Arch commands.

loqs · 2018-05-12 22:02:12

Systemd#Using_units

Caeruleas · 2018-05-12 22:20:26

Thank you all, after masking the service (thanks to loqs' link) the error doesn't show anymore.

seth · 2018-05-13 07:44:59

Out of curiosity (more or less), do you have udev rules in place to remove the backlight device or maybe unload some module?

Check your dmesg & journal; if the service is autogenerated, there should™ at some point have been a /sys/class/backlight/acpi_video0, so if it's not there at runtime, it also must have been removed or renamed or something. This might point to a deeper problem (eg. a crashing kernel module)

Arch Linux

#1 2018-05-12 05:45:42

Screen Backlight Error [SOLVED]

#2 2018-05-12 06:44:19

Re: Screen Backlight Error [SOLVED]

#3 2018-05-12 07:01:11

Re: Screen Backlight Error [SOLVED]

#4 2018-05-12 21:44:23

Re: Screen Backlight Error [SOLVED]

#5 2018-05-12 21:49:02

Re: Screen Backlight Error [SOLVED]

#6 2018-05-12 22:00:33

Re: Screen Backlight Error [SOLVED]

#7 2018-05-12 22:02:12

Re: Screen Backlight Error [SOLVED]

#8 2018-05-12 22:20:26

Re: Screen Backlight Error [SOLVED]

#9 2018-05-13 07:44:59

Re: Screen Backlight Error [SOLVED]

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