Mesa (master): egl/wayland: Ignore rects from SwapBuffersWithDamage

[Daniel Stone]

Module: Mesa
Branch: master
Commit: d1314de293e9e4a63c35f094c3893aaaed8580b4
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d1314de293e9e4a63c35f094c3893aaaed8580b4

Author: Daniel Stone <daniels at collabora.com>
Date:   Sat Nov  7 18:25:31 2015 +0000

egl/wayland: Ignore rects from SwapBuffersWithDamage

eglSwapBuffersWithDamage accepts damage-region rectangles to hint the
compositor that it only needs to redraw certain areas, which was passed
through the wl_surface_damage request, as designed.

Wayland also offers a buffer transformation interface, e.g. to allow
users to render pre-rotated buffers. Unfortunately, there is no way to
query buffer transforms, and the damage region was provided in surface,
rather than buffer, co-ordinate space.

Users could in theory account for this themselves, but EGL also requires
co-ordinates to be passed in GL/mathematical co-ordinate space, with an
inversion to Wayland's natural/scanout co-ordinate space, so
transformations other than a 180-degree rotation will fail as EGL
attempts to subtract the region from (its view of the) surface height.

Pending creation and acceptance of a wl_surface.buffer_damage request,
which will accept co-ordinates in buffer co-ordinate space, pessimise to
always sending full-surface damage.

bce64c6c provides the explanation for why we send maximum-range damage,
rather than the full size of the surface: in the presence of buffer
transformations, full-surface damage may not actually cover the entire
surface.

Signed-off-by: Daniel Stone <daniels at collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>

---

 src/egl/drivers/dri2/platform_wayland.c |   16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 0d161f6..a635c75 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -703,18 +703,10 @@ dri2_wl_swap_buffers_with_damage(_EGLDriver *drv,
    dri2_surf->dx = 0;
    dri2_surf->dy = 0;
 
-   if (n_rects == 0) {
-      wl_surface_damage(dri2_surf->wl_win->surface,
-                        0, 0, INT32_MAX, INT32_MAX);
-   } else {
-      for (i = 0; i < n_rects; i++) {
-         const int *rect = &rects[i * 4];
-         wl_surface_damage(dri2_surf->wl_win->surface,
-                           rect[0],
-                           dri2_surf->base.Height - rect[1] - rect[3],
-                           rect[2], rect[3]);
-      }
-   }
+   /* We deliberately ignore the damage region and post maximum damage, due to
+    * https://bugs.freedesktop.org/78190 */
+   wl_surface_damage(dri2_surf->wl_win->surface,
+                     0, 0, INT32_MAX, INT32_MAX);
 
    if (dri2_dpy->is_different_gpu) {
       _EGLContext *ctx = _eglGetCurrentContext();