/usr/share/X11/xorg.conf.d/20-radeon.conf contains some
configuration workarounds for the radeon driver. They are
commented by default (that is, they are all prefixed by the hash
(#) character), which means they are not active. To activate
them, you need to remove the hashes.
The configuration comes in blocks or sections. A section starts
with "Section" and ends with "EndSection". You must remove (to
activate) or add (to de-activate) hashes for a complete section,
not only to a part of them.
The file above contains multiple sections, one for each
workaround. Each workaround address a different problem. Please
ensure that you only activate one of them. If you
enable multiple sections, the result will be unpredictable.
The first workaround (the first section in the file) is to
address tearing or overall poor 2D performance.
The second workaround (the second section in the file) is to
address freeze or locks-up when powering down the machine, or
when launching Xlock screen locking, or small 2D graphics