Comment 180 for bug 1173725

Hi,
Thinkpad T430 here (without the s), I'm using linux 3.13.4 and systemd 208 from arch linux booting in bios mode with the last bios update (2.62).

The bug seems the same as for T430s and I can "fix" it with acpi_osi='!Windows 2012' or using video.use_native_backlight=1 as kernel command line in grub.

It works kinda well with video.use_native_backlight=1 except that I have now 4437 level of brightness in /sys/class/backlight/intel_backlight and as reported by Weber, systemd complains about this:

[ 9.226063] thinkpad_acpi: Unsupported brightness interface, please contact <email address hidden>

System Information
        Manufacturer: LENOVO
        Product Name: 2349KDG
        Version: ThinkPad T430
        (...)
        Wake-up Type: Power Switch
        SKU Number: LENOVO_MT_2349
        Family: ThinkPad T430

It is because of so many levels of backlight that I have in KDE this behavior switching brightness with the keys:
from 0 to 100: 0-10-20-30-40-50-60-70-80-90-100
from 100 to 0: 100-89-79-69...etc.