Module: Mesa Branch: master Commit: 1f2d0093bf5084f65a923582881dc74153c804a4 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=1f2d0093bf5084f65a923582881dc74153c804a4
Author: Daniel Stone <dani...@collabora.com> Date: Mon May 15 22:22:32 2017 +0100 egl/wayland: Ensure we get a back buffer Commit 9ca6711faa03 changed the Wayland winsys to only block for the frame callback inside SwapBuffers, rather than get_back_bo. get_back_bo would perform a single non-blocking Wayland event dispatch, to try to find any release events which we had pulled off the wire but not actually processed. The blocking dispatch was moved to SwapBuffers. This removed a guarantee that we would've processed all events inside get_back_bo(), and introduced a failure whereby the server could've sent a buffer release event, but we wouldn't have read it. In clients unconstrained by SwapInterval (rendering ~as fast as possible), which were being displayed directly without composition (buffer release delayed), this could lead to get_back_bo() failing because there were no free buffers available to it. The drawing rightly failed, but this was papered over because of the path in eglSwapBuffers() which attempts to guarantee a BO, in order to support calling SwapBuffers twice in a row with no rendering actually having been performed. Since eglSwapBuffers will perform a blocking dispatch of Wayland events, a buffer release would have arrived by that point, and we could then choose a buffer to post to the server. The effect was that frames were displayed out-of-order, since we grabbed a frame with random past content to display to the compositor. Ideally get_back_bo() failing should store a failure flag inside the surface and cause the next SwapBuffers to fail, but for the meantime, restore the correct behaviour such that get_back_bo() no longer fails. Signed-off-by: Daniel Stone <dani...@collabora.com> Reported-by: Eero Tamminen <eero.t.tammi...@intel.com> Acked-by: Pekka Paalanen <pekka.paala...@collabora.co.uk> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98833 Fixes: 9ca6711faa03 ("Revert "wayland: Block for the frame callback in get_back_bo not dri2_swap_buffers"") --- src/egl/drivers/dri2/platform_wayland.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c index 52ab9f7579..29f64f3a1e 100644 --- a/src/egl/drivers/dri2/platform_wayland.c +++ b/src/egl/drivers/dri2/platform_wayland.c @@ -353,7 +353,7 @@ get_back_bo(struct dri2_egl_surface *dri2_surf) /* There might be a buffer release already queued that wasn't processed */ wl_display_dispatch_queue_pending(dri2_dpy->wl_dpy, dri2_surf->wl_queue); - if (dri2_surf->back == NULL) { + while (dri2_surf->back == NULL) { for (i = 0; i < ARRAY_SIZE(dri2_surf->color_buffers); i++) { /* Get an unlocked buffer, preferrably one with a dri_buffer * already allocated. */ @@ -364,6 +364,14 @@ get_back_bo(struct dri2_egl_surface *dri2_surf) else if (dri2_surf->back->dri_image == NULL) dri2_surf->back = &dri2_surf->color_buffers[i]; } + + if (dri2_surf->back) + break; + + /* If we don't have a buffer, then block on the server to release one for + * us, and try again. */ + if (wl_display_dispatch_queue(dri2_dpy->wl_dpy, dri2_surf->wl_queue) < 0) + return -1; } if (dri2_surf->back == NULL) _______________________________________________ mesa-commit mailing list mesa-commit@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-commit
