/etc/X11/xorg.conf.d/20-radeon.conf

Section "Module"
    Load "dri3"
    Load "glamoregl"
EndSection

Section "Device"
    Identifier  "Radeon"
    Driver "radeon"
    Option "Accel" "on"
    Option "RenderAccel" "on"
    Option "DRI" "3"
    Option "AccelMethod" "glamor"
    Option "ColorTiling" "on"
    Option "ColorTiling2D" "on"
    Option "TearFree" "on"
EndSection