I have a usb key with true os instaled and the brightness work . but true os is not a good bsd .

ok i have do this method and xorg dont work , i have this message : [KMS] drm report modesetting isn t supported

hello!! i have a laptop acer es1 with radeon R3 and i can t set the brightness . i tried xrandr i have this : xrandr: Failed to get size of gamma for output default Screen 0: minimum 1366 x 768, current 1368 x 768, maximum 1368 x 768 default connected 1368x768+0+0 0mm x 0mm 1366x768 0.00 1368x768 0....