Comment 6 for bug 1587744

@Alberto, @Franz,

Blacklisted Radeon with the following:
$ echo 'blacklist radeon' | sudo tee /etc/modprobe.d/blacklist-radeon.conf
$ sudo reboot

Results:

1. Saw the following in dmesg output:
[ 3.914125] [drm] amdgpu kernel modesetting enabled.

2. But the screen is still dark and still cannot modify brightness level via brightness settings.