From 9e73df9095b1db9be9f915cbef2f7ab8d46de7c5 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Sat, 15 Oct 2016 00:17:18 +0100
Subject: [PATCH] dri3

---
 src/loader/loader_dri3_helper.c | 44 ++++++++++++++++++++++++++++++++++++++++-
 src/loader/loader_dri3_helper.h |  3 +++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_helper.c
index cb52bfa..f55f766 100644
--- a/src/loader/loader_dri3_helper.c
+++ b/src/loader/loader_dri3_helper.c
@@ -139,6 +139,11 @@ loader_dri3_drawable_fini(struct loader_dri3_drawable *draw)
    for (int i = 0; i < LOADER_DRI3_MAX_BACK; i++)
       dri3_free_render_buffer(draw, draw->back[i].buffer);
 
+   if (draw->sync_fence) {
+      xcb_sync_destroy_fence(draw->conn, draw->sync_fence);
+      xshmfence_unmap_shm(draw->shm_fence);
+   }
+
    if (draw->special_event) {
       xcb_void_cookie_t cookie =
          xcb_present_select_input_checked(draw->conn, draw->eid, draw->drawable,
@@ -587,7 +592,19 @@ loader_dri3_wait_x(struct loader_dri3_drawable *draw)
 {
    struct loader_dri3_buffer *front;
 
-   if (draw == NULL || !draw->have_fake_front)
+   if (draw == NULL)
+      return;
+
+   if (draw->sync_fence) {
+      xshmfence_reset(draw->shm_fence);
+
+      xcb_sync_trigger_fence(draw->conn, draw->sync_fence);
+      xcb_flush(draw->conn);
+
+      xshmfence_await(draw->shm_fence);
+   }
+
+   if (!draw->have_fake_front)
       return;
 
    front = dri3_fake_front_buffer(draw);
@@ -976,6 +993,29 @@ no_shm_fence:
    return NULL;
 }
 
+static void
+dri3_attach_sync(struct loader_dri3_drawable *draw)
+{
+   int fence_fd;
+
+   fence_fd = xshmfence_alloc_shm();
+   if (fence_fd < 0)
+      return;
+
+   draw->shm_fence = xshmfence_map_shm(fence_fd);
+   if (draw->shm_fence == NULL) {
+      close(fence_fd);
+      return;
+   }
+
+   draw->sync_fence = xcb_generate_id(draw->conn);
+   xcb_dri3_fence_from_fd(draw->conn,
+                          draw->drawable,
+                          draw->sync_fence,
+                          false,
+                          fence_fd);
+}
+
 /** loader_dri3_update_drawable
  *
  * Called the first time we use the drawable and then
@@ -1063,6 +1103,8 @@ dri3_update_drawable(__DRIdrawable *driDrawable,
          draw->is_pixmap = true;
          xcb_unregister_for_special_event(draw->conn, draw->special_event);
          draw->special_event = NULL;
+
+         dri3_attach_sync(draw);
       }
    }
    dri3_flush_present_events(draw);
diff --git a/src/loader/loader_dri3_helper.h b/src/loader/loader_dri3_helper.h
index 1dd0e33..af5600f 100644
--- a/src/loader/loader_dri3_helper.h
+++ b/src/loader/loader_dri3_helper.h
@@ -150,6 +150,9 @@ struct loader_dri3_drawable {
    xcb_gcontext_t gc;
    xcb_special_event_t *special_event;
 
+   xcb_sync_fence_t sync_fence;
+   struct xshmfence *shm_fence;
+
    bool first_init;
 
    struct loader_dri3_extensions *ext;
-- 
2.7.4