vk: fix headless semaphore wait logic

We removed the no-op queue submit for headless in PR #7264. This means that a semaphore will not be waited on and caused a validation error. Here, we simply don't acquire that semaphore for present. Also reorganzied the pSempaphores array code for better readability. Fixes #7334
google · Nov 3, 2023 · cd558c7 · cd558c7
1 parent 974a69a
commit cd558c7
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Showing 2 changed files with 19 additions and 22 deletions.
diff --git a/filament/backend/src/vulkan/VulkanCommands.cpp b/filament/backend/src/vulkan/VulkanCommands.cpp
@@ -268,33 +268,25 @@ bool VulkanCommands::flush() {
             VK_NULL_HANDLE,
             VK_NULL_HANDLE,
     };
-
+    uint32_t waitSemaphoreCount = 0;
+    if (mSubmissionSignal) {
+        signals[waitSemaphoreCount++] = mSubmissionSignal;
+    }
+    if (mInjectedSignal) {
+        signals[waitSemaphoreCount++] = mInjectedSignal;
+    }
     VkCommandBuffer const cmdbuffer = currentbuf->buffer();
-
     VkSubmitInfo submitInfo{
             .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
-            .waitSemaphoreCount = 0,
-            .pWaitSemaphores = signals,
+            .waitSemaphoreCount = waitSemaphoreCount,
+            .pWaitSemaphores = waitSemaphoreCount > 0 ? signals : nullptr,
             .pWaitDstStageMask = waitDestStageMasks,
             .commandBufferCount = 1,
             .pCommandBuffers = &cmdbuffer,
             .signalSemaphoreCount = 1u,
             .pSignalSemaphores = &renderingFinished,
     };
 
-    if (mSubmissionSignal) {
-        signals[submitInfo.waitSemaphoreCount++] = mSubmissionSignal;
-    }
-
-    if (mInjectedSignal) {
-        signals[submitInfo.waitSemaphoreCount++] = mInjectedSignal;
-    }
-
-    // To address a validation warning.
-    if (submitInfo.waitSemaphoreCount == 0) {
-        submitInfo.pWaitSemaphores = VK_NULL_HANDLE;
-    }
-
 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
     slog.i << "Submitting cmdbuffer=" << cmdbuffer
            << " wait=(" << signals[0] << ", " << signals[1] << ") "

diff --git a/filament/backend/src/vulkan/VulkanSwapChain.cpp b/filament/backend/src/vulkan/VulkanSwapChain.cpp
@@ -99,11 +99,16 @@ void VulkanSwapChain::present() {
         mColors[mCurrentSwapIndex]->transitionLayout(cmdbuf, subresources, VulkanLayout::PRESENT);
     }
     mCommands->flush();
-    VkSemaphore const finishedDrawing = mCommands->acquireFinishedSignal();
-    VkResult const result = mPlatform->present(swapChain, mCurrentSwapIndex, finishedDrawing);
-    ASSERT_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR
-                                 || result == VK_ERROR_OUT_OF_DATE_KHR,
-            "Cannot present in swapchain.");
+
+    // We only present if it is not headless.  No-op for headless (but note that we still need the
+    // flush() in the above line).
+    if (!mHeadless) {
+        VkSemaphore const finishedDrawing = mCommands->acquireFinishedSignal();
+        VkResult const result = mPlatform->present(swapChain, mCurrentSwapIndex, finishedDrawing);
+        ASSERT_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR ||
+                                     result == VK_ERROR_OUT_OF_DATE_KHR,
+                "Cannot present in swapchain.");
+    }
 
     // We presented the last acquired buffer.
     mAcquired = false;