File 0018-Replace-SurfaceFeedbackState-modifiers_changed-with-.patch of Package libnvidia-egl-wayland2

From a6d6523b6b7ec9e5649a0dd13d417586d814e209 Mon Sep 17 00:00:00 2001
From: Kyle Brenneman <kbrenneman@nvidia.com>
Date: Wed, 10 Dec 2025 08:19:14 -0700
Subject: [PATCH 18/18] Replace SurfaceFeedbackState::modifiers_changed with a
 counter

Currently, we set the modifiers_changed flag upon receiving new surface
feedback data, but we never clear it, and there isn't a good place to do
so.

We shouldn't clear the flag after calling SwapChainRealloc in
SwapBuffers, because we haven't set the new swapchain yet, and we might
hit an error before we actually call SetWindowSwapchain.

We also shouldn't clear the flag when we call SetWindowSwapchain,
because it's possible that another round of feedback data could arrive
between SwapChainRealloc and SetWindowSwapchain.

Instead, replace the modifiers_changed flag with a counter that we
increment when we get a zwp_linux_dmabuf_feedback_v1::done event, and
we record the value of that counter in WlSwapChain. If the swapchain's
counter doesn't match the window's counter, then we know we need to scan
the modifier list again.
---
 src/wayland/wayland-surface.c   | 31 ++++++++++++++++++++++++++-----
 src/wayland/wayland-swapchain.h |  2 ++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/wayland/wayland-surface.c b/src/wayland/wayland-surface.c
index f34489e..298b08a 100644
--- a/src/wayland/wayland-surface.c
+++ b/src/wayland/wayland-surface.c
@@ -88,9 +88,12 @@ typedef struct
     EGLBoolean tranche_linear_supported;
 
     /**
-     * True if we've received new feedback data.
+     * A counter that we increment when we get a new round of feedback events.
+     *
+     * We record this counter in WlSwapChain to keep track of whether we need
+     * to reallocate the swapchain with a different modifier.
      */
-    EGLBoolean modifiers_changed;
+    uint32_t feedback_update_count;
 } SurfaceFeedbackState;
 
 struct _EplImplSurface
@@ -429,7 +432,7 @@ static void OnSurfaceFeedbackDone(void *userdata,
 
     state->linear_supported = EGL_FALSE;
     state->tranche_linear_supported = EGL_FALSE;
-    state->modifiers_changed = EGL_TRUE;
+    state->feedback_update_count++;
     eplWlDmaBufFeedbackCommonDone(&state->base);
 }
 
@@ -559,7 +562,8 @@ static EGLBoolean SwapChainRealloc(EplSurface *psurf,
     }
     else if (allow_modifier_realloc
             && psurf->priv->current.feedback != NULL
-            && psurf->priv->current.feedback->modifiers_changed)
+            && psurf->priv->current.feedback->feedback_update_count
+                != psurf->priv->current.swapchain->feedback_update_count)
     {
         if (psurf->priv->current.swapchain->prime)
         {
@@ -571,18 +575,28 @@ static EGLBoolean SwapChainRealloc(EplSurface *psurf,
         }
         else
         {
+            // We might need to transition from direct to either prime or
+            // direct with different modifiers.
             size_t i;
             needs_new = EGL_TRUE;
             for (i=0; i<psurf->priv->current.num_surface_modifiers; i++)
             {
                 if (psurf->priv->current.swapchain->modifier == psurf->priv->current.surface_modifiers[i])
                 {
-                    // Transition from direct to either prime or direct with different modifiers
+                    // The current modifier is still valid.
                     needs_new = EGL_FALSE;
                     break;
                 }
             }
         }
+
+        if (!needs_new)
+        {
+            // If the current modifier is still valid, then record the current
+            // feedback count so that we know not to check again next frame.
+            psurf->priv->current.swapchain->feedback_update_count =
+                psurf->priv->current.feedback->feedback_update_count;
+        }
     }
 
     if (needs_new)
@@ -604,6 +618,13 @@ static EGLBoolean SwapChainRealloc(EplSurface *psurf,
         {
             goto done;
         }
+        if (psurf->priv->current.feedback != NULL)
+        {
+            // Record the current feedback update count. In SwapChainRealloc,
+            // we'll use this to check if we need to reallocate the swapchain
+            // with different modifiers.
+            swapchain->feedback_update_count = psurf->priv->current.feedback->feedback_update_count;
+        }
     }
 
     success = EGL_TRUE;
diff --git a/src/wayland/wayland-swapchain.h b/src/wayland/wayland-swapchain.h
index 5358bc3..3316a03 100644
--- a/src/wayland/wayland-swapchain.h
+++ b/src/wayland/wayland-swapchain.h
@@ -175,6 +175,8 @@ typedef struct
      * An event queue used internally by the swap chain itself.
      */
     struct wl_event_queue *queue;
+
+    uint32_t feedback_update_count;
 } WlSwapChain;
 
 /**
-- 
2.51.0