From ea975896242fba4a92d68c8fb45751e60ed826cc Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Mon, 10 Jun 2019 22:58:20 -0400
Subject: nvflinger: Acquire buffers in the same order as they were queued.

---
 src/core/hle/service/nvflinger/buffer_queue.cpp | 12 +++++++++---
 src/core/hle/service/nvflinger/buffer_queue.h   |  2 ++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/core/hle/service/nvflinger/buffer_queue.cpp b/src/core/hle/service/nvflinger/buffer_queue.cpp
index 75e47b8c7..d8aa3f1c0 100644
--- a/src/core/hle/service/nvflinger/buffer_queue.cpp
+++ b/src/core/hle/service/nvflinger/buffer_queue.cpp
@@ -75,12 +75,18 @@ void BufferQueue::QueueBuffer(u32 slot, BufferTransformFlags transform,
     itr->crop_rect = crop_rect;
     itr->swap_interval = swap_interval;
     itr->multi_fence = multi_fence;
+    queue_sequence.push_back(slot);
 }
 
 std::optional<std::reference_wrapper<const BufferQueue::Buffer>> BufferQueue::AcquireBuffer() {
-    auto itr = std::find_if(queue.begin(), queue.end(), [](const Buffer& buffer) {
-        return buffer.status == Buffer::Status::Queued;
-    });
+    std::vector<Buffer>::iterator itr = queue.end();
+    while (itr == queue.end() && !queue_sequence.empty()) {
+        u32 slot = queue_sequence.front();
+        itr = std::find_if(queue.begin(), queue.end(), [&slot](const Buffer& buffer) {
+            return buffer.status == Buffer::Status::Queued && buffer.slot == slot;
+        });
+        queue_sequence.pop_front();
+    }
     if (itr == queue.end())
         return {};
     itr->status = Buffer::Status::Acquired;
diff --git a/src/core/hle/service/nvflinger/buffer_queue.h b/src/core/hle/service/nvflinger/buffer_queue.h
index c163e565c..be993ee61 100644
--- a/src/core/hle/service/nvflinger/buffer_queue.h
+++ b/src/core/hle/service/nvflinger/buffer_queue.h
@@ -6,6 +6,7 @@
 
 #include <optional>
 #include <vector>
+#include <list>
 
 #include "common/common_funcs.h"
 #include "common/math_util.h"
@@ -97,6 +98,7 @@ private:
     u64 layer_id;
 
     std::vector<Buffer> queue;
+    std::list<u32> queue_sequence;
     Kernel::EventPair buffer_wait_event;
 };
 
-- 
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