uses the xserver-xorg-video-amdgpu package, not available in debian jessie, but available in stretch. Currently running arch though for best compatibility.
- backlight needs special kernel parameters.
----- " acpi=force acpi_backlight=vendor "
And the usual echo ### > /sys/class/backlight/amdgpu_b10/brightness
where ### is 0 - 255 changes the brightness of the LCD, 0 being off
xbacklight doesn't seem to recognize the device, although same issue going from debian jessie to stretch for my hp stream 11.
The /sys/class/... is root:root by default, so change that after boot if you want the user to use it, otherwise only as root does it work.
Thank you !!