Mesa (staging/20.1): vulkan/wsi/x11: wait for acquirable images in FIFO mode

[GitLab Mirror]

Module: Mesa
Branch: staging/20.1
Commit: d8b03e72f455d037763d56157096af5a52f1e740
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d8b03e72f455d037763d56157096af5a52f1e740

Author: Roman Gilg <subdiff at gmail.com>
Date:   Mon Aug 31 11:35:16 2020 +0200

vulkan/wsi/x11: wait for acquirable images in FIFO mode

In FIFO presentation mode we block either on our present-queue or on Present
events after an image was transmitted.

In case we receive completion events without idle events at some point we
exhaust our acquire-queue and can not block anymore on present-queue.

Ensure that the consumer has at least one image to acquire before blocking
again on present-queue. Otherwise wait for one from the X server.

CC: mesa-stable
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3344
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Reviewed-by: Simon Ser <contact at emersion.fr>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6513>
(cherry picked from commit ec5e918ef4911d09b5611773bc58952b13ccef38)

---

 .pick_status.json               |  2 +-
 src/vulkan/wsi/wsi_common_x11.c | 15 +++++++++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 57a91f02bc5..eac0d44ef47 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -274,7 +274,7 @@
         "description": "vulkan/wsi/x11: wait for acquirable images in FIFO mode",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": null
     },
diff --git a/src/vulkan/wsi/wsi_common_x11.c b/src/vulkan/wsi/wsi_common_x11.c
index da02569e94b..4cc03640ef2 100644
--- a/src/vulkan/wsi/wsi_common_x11.c
+++ b/src/vulkan/wsi/wsi_common_x11.c
@@ -1112,11 +1112,9 @@ x11_manage_fifo_queues(void *state)
 
    assert(chain->has_present_queue);
    while (chain->status >= 0) {
-      /* It should be safe to unconditionally block here.  Later in the loop
-       * we blocks until the previous present has landed on-screen.  At that
-       * point, we should have received IDLE_NOTIFY on all images presented
-       * before that point so the client should be able to acquire any image
-       * other than the currently presented one.
+      /* We can block here unconditionally because after an image was sent to
+       * the server (later on in this loop) we ensure at least one image is
+       * acquirable by the consumer or wait there on such an event.
        */
       uint32_t image_index = 0;
       result = wsi_queue_pull(&chain->present_queue, &image_index, INT64_MAX);
@@ -1149,7 +1147,12 @@ x11_manage_fifo_queues(void *state)
          goto fail;
 
       if (chain->has_acquire_queue) {
-         while (chain->last_present_msc < target_msc) {
+         /* Wait for our presentation to occur and ensure we have at least one
+          * image that can be acquired by the client afterwards. This ensures we
+          * can pull on the present-queue on the next loop.
+          */
+         while (chain->last_present_msc < target_msc ||
+                chain->sent_image_count == chain->base.image_count) {
             xcb_generic_event_t *event =
                xcb_wait_for_special_event(chain->conn, chain->special_event);
             if (!event) {