One of the lacking features with output offloading was
that screen rotation didn't work at all.
This patch makes 0/90/180/270 rotation work with USB output
and GPU outputs.
When it allocates the shared pixmap it allocates it rotated,
and any updates to the shared pixmap are done using a composite
path that does the rotation. The slave GPU then doesn't need
to know about the rotation and just displays the pixmap.
v2:
rewrite the sync dirty helper to use the dst pixmap, and
avoid any strange hobbits and rotations.
This breaks ABI in two places.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Keith Packard <keithp@keithp.com>