Comment 49 for bug 1270579

Hello,
inside "/sys/class/backlight/" I have two folders: "acpi_video0" and "acpi_video1":

~$ systemctl status systemd-backlight@backlight:acpi_video0.service
● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight B
   Loaded: loaded (/lib/systemd/system/systemd-backlight@.service; static; vendo
   Active: active (exited) since Sat 2017-04-08 13:37:31 CEST; 16min ago
     Docs: man:systemd-backlight@.service(8)
 Main PID: 683 (code=exited, status=0/SUCCESS)

~$ systemctl status systemd-backlight@backlight:acpi_video1.service
● systemd-backlight@backlight:acpi_video1.service - Load/Save Screen Backlight B
   Loaded: loaded (/lib/systemd/system/systemd-backlight@.service; static; vendo
   Active: active (exited) since Sat 2017-04-08 13:37:31 CEST; 22min ago
     Docs: man:systemd-backlight@.service(8)
 Main PID: 684 (code=exited, status=0/SUCCESS)

Today I received many Ubuntu updates (kernel included), and I also installed freshly released Nvidia 381.09 driver (via “Graphics Drivers” team - Proprietary GPU Drivers PPA).
Now brightness settings are correctly saved, but I have a new problem: changing brightness level doesn't produce any effect (both with or without Nvidia driver installed).