tree 80bc212893431b25b9975f0caa5327acdef523a2
parent 902d803fa6c629f8aa1c31ca96aa460235cccd01
author Nico Huber <nico.huber@secunet.com> 1601900157 +0200
committer Nico Huber <nico.h@gmx.de> 1785394171 +0000

gma pipe_setup: Use a plane as cursor in case of y-tiling

Y-tiling allows us to rotate the framebuffer in 90° steps. However,
we'd also want to rotate the cursor. We can use a second (framebuffer)
plane but that has some pitfalls:

* The plane has to be completely within the visible picture, hence we
  can't move the cursor partially out of the picture and have to clip
  it manually.
* Calculating the offsets for the clipping is not easy considering
  the rotation involved. We translate the cursor's position on the
  framebuffer to the final position on the visible picture first,
  then we calculate the offsets. This makes it harder to compare to
  the documented offset calculations.

Because of this, we have to re-write most of the plane registers when
the cursor is clipped. Only when the cursor was and is fully visible,
we can simply "move" its position.

Change-Id: Ibd6258304ef7d9555b279b5e243a8c1aeadbbb93
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.sourcearcade.org/c/libgfxinit/+/546
Reviewed-by: Thomas Heijligen <src@posteo.de>
Tested-by: Nico Huber <nico.h@gmx.de>