When using reverse prime we do 2 copies, 1 from the primary GPU's
framebuffer to a shared pixmap and 1 from the shared pixmap to the
secondary GPU's framebuffer.
This means that on the primary GPU side the copy MUST be finished,
before we start the second copy (before the secondary GPU's driver
starts processing the damage on the shared pixmap).
This fixes secondary outputs sometimes showning (some) old fb contents,
because of the 2 copies racing with each other, for an example of
what this looks like see:
https://fedorapeople.org/~jwrdegoede/IMG_20160915_130555.jpg
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
e8695100b1
