When we can trivially calculate the affected source regions, do that before calling region bounded prepareAccess. [ Michel: Minor fixups to address compiler warnings ] Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Michel Dänzer <daenzer@vmware.com> Acked-by: Maarten Maathuis <madman2003@gmail.com> Signed-off-by: Keith Packard <keithp@keithp.com>