In finally managed to resolve the issue for my T430s. I had to add the
following boot options to /etc/default/grub:
acpi_osi='!Windows 2012'
- This makes the OSD work properly with 8 brightness steps
video.brightness_switch_enabled=0
- This allows you to have 15 brightness steps (working OSD also
For my Thinkpad T430s, I can confirm that adding acpi_backlight=vendor
as a grub boot option fixes the problem. I only have the Intel GPU
enabled.
However, applying this boot options result in the OSD not correctly
showing the current brightness state (s. attachment); it has always the
same state.
