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@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 0d161f617a1935f8e272c3cdb5e0532f87a136fb..a635c758da122c8079005f57e24600232a7385bd 100644 (file)
--- 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();