[systemd-devel] systemd backlight:acpi_video0 fails, no such device

[Chris Murphy]

On Mon, Sep 2, 2019 at 1:56 AM Hans de Goede <hdegoede at redhat.com> wrote:
>
> Hi,
>
> On 02-09-19 07:17, Mantas Mikulėnas wrote:
> > On Mon, Sep 2, 2019 at 7:34 AM Chris Murphy <lists at colorremedies.com <mailto:lists at colorremedies.com>> wrote:
> >
> >     systemd-243~rc2-2.fc31.x86_64
> >     kernel-5.3.0-0.rc6.git1.1.fc32.x86_64
> >
> >     This might be a regression, at least I don't remember this happening
> >     before. I can use the expected keys for built-in display brightness,
> >     and built-in keyboard brightness. But the service unit fails with an
> >     out of the box installation.
> >
> >
> >     [chris at fmac ~]$ sudo systemctl status
> >     systemd-backlight at backlight:acpi_video0.service
> >     ● systemd-backlight at backlight:acpi_video0.service - Load/Save Screen
> >     Backlight Brightness of backlight:acpi_video0
> >         Loaded: loaded (/usr/lib/systemd/system/systemd-backlight at .service;
> >     static; vendor preset: disabled)
> >         Active: failed (Result: exit-code) since Sun 2019-09-01 19:57:37
> >     MDT; 8min ago
> >           Docs: man:systemd-backlight at .service(8)
> >        Process: 667 ExecStart=/usr/lib/systemd/systemd-backlight load
> >     backlight:acpi_video0 (code=exited, status=1/FAILURE)
> >       Main PID: 667 (code=exited, status=1/FAILURE)
> >
> >     Sep 01 19:57:37 fmac.local systemd[1]: Starting Load/Save Screen
> >     Backlight Brightness of backlight:acpi_video0...
> >     Sep 01 19:57:37 fmac.local systemd-backlight[667]: Failed to get
> >     backlight or LED device 'backlight:acpi_video0': No such device
> >     Sep 01 19:57:37 fmac.local systemd[1]:
> >     systemd-backlight at backlight:acpi_video0.service: Main process exited,
> >     code=exited, status=1/FAILURE
> >     Sep 01 19:57:37 fmac.local systemd[1]:
> >     systemd-backlight at backlight:acpi_video0.service: Failed with result
> >     'exit-code'.
> >     Sep 01 19:57:37 fmac.local systemd[1]: Failed to start Load/Save
> >     Screen Backlight Brightness of backlight:acpi_video0.
> >     [chris at fmac ~]$
> >
> >     # find /sys -name "*video0*"
> >     /sys/class/video4linux/video0
> >     /sys/devices/pci0000:00/0000:00:1a.7/usb1/1-2/1-2:1.0/video4linux/video0
> >     # ls -l /sys/class/backlight/
> >     total 0
> >     lrwxrwxrwx. 1 root root 0 Sep  1 19:57 gmux_backlight ->
> >     ../../devices/pnp0/00:03/backlight/gmux_backlight
> >     lrwxrwxrwx. 1 root root 0 Sep  1 19:57 intel_backlight ->
> >     ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
> >
> >
> > Could it be that acpi_backlight is loaded at first, but gets replaced by intel_backlight before systemd could react?
>
> Maybe, the gmux_backlight suggests that this is a macbook.

It is a 2011 Macbook Pro.


-- 
Chris Murphy