From 8655f6df6bd9eff27bb6600aa0e19bba8af0198c Mon Sep 17 00:00:00 2001
From: Willem Melching <willem.melching@gmail.com>
Date: Tue, 4 Jan 2022 15:55:28 +0100
Subject: [PATCH] cameraview.cc: call glFlush after creating fence

---
 selfdrive/ui/qt/widgets/cameraview.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/selfdrive/ui/qt/widgets/cameraview.cc b/selfdrive/ui/qt/widgets/cameraview.cc
index b390f5cdb2322e..51553bcc8f34f4 100644
--- a/selfdrive/ui/qt/widgets/cameraview.cc
+++ b/selfdrive/ui/qt/widgets/cameraview.cc
@@ -309,6 +309,10 @@ void CameraViewWidget::vipcThread() {
           assert(glGetError() == GL_NO_ERROR);
 
           wait_fence.reset(new WaitFence());
+
+          // Ensure the fence is in the GPU command queue, or waiting on it might block
+          // https://www.khronos.org/opengl/wiki/Sync_Object#Flushing_and_contexts
+          glFlush();
         }
         latest_texture_id = buf->idx;
       }