We initially assumed that copy_sub_buffer is synchronized on
which is only the case for a subset of GPUs for example it is not
synchronized on INTEL gen6 and gen7, so we remove this assumption
for now.
We should have a specific driver / GPU whitelist if we want to enable
this.
https://bugzilla.gnome.org/show_bug.cgi?id=669122
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Reviewed-by: Neil Roberts <neil@linux.intel.com>
fd31da45e2