I've got a Lenovo Thinkpad P71 with the NVidia Quadro P3000, that has the Discrete Graphics setting on the BIOS, and I'm using the proprietary drivers on Debian 9.For some reason, the brightness keys do not work (Fn+F5/Fn+F6)I've tried adding Option RegistryDwords EnableBrightnessControl=1 to my xorg.conf, adding pcie_aspm=force, acpi_osi=, acpi_osi=Linux, and acpi_backlight=vendor (individually) to my kernel parameters, doing update-grub, and rebooting, but nothing seems to work.Currently, my kernel parameters are quiet splash acpi_osi= and I have EnableBrightnessControl=1 on my xorg.conf, and the brightness keys appear to work, but won't go past what appears to be 10% on the pop-up, and the actual brightness doesn't actually adjust.In /sys/class/backlight/thinkpad_screen/ I have brightness, bl_power, max_brightness, and actual_brightness, but adjusting these does not work, and when I try using the Fn+F5/F6 keys, the values are reset to 0. (except for max_brightness, which stays at 15)Additionally, xbacklight only works when I don't have acpi_osi= in my kernel parameters.
Brightness key issue on Lenovo P71
acpi;thinkpad;brightness;backlight