Add an env var to periodically kill the device on d3d

...in order to test the handling of losing the device.

The D3D11 backend of QRhi provides a convenient way to test this.
Hook it up to a QSG_RHI_SIMULATE_DEVICE_LOSS environment variable.
The value is the number of frames to wait before breaking the
ID3D11Device.

We cannot currently recover from a device loss. Hence the importance
of being able to test in a simple way. The rhi code path needs to be
brought up to the level of the direct OpenGL path in this respect,
in separate patches.

Change-Id: I66d6315dc60a9673903da9bed36de0cdd115f4a7
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

2 files changed, 9 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrhisupport.cpp b/src/quick/scenegraph/qsgrhisupport.cpp
index e050938cc9..2c5d8fb2ac 100644
--- a/src/quick/scenegraph/qsgrhisupport.cpp
+++ b/src/quick/scenegraph/qsgrhisupport.cpp
@@ -178,6 +178,10 @@ void QSGRhiSupport::applySettings()
 
     m_shaderEffectDebug = qEnvironmentVariableIntValue("QSG_RHI_SHADEREFFECT_DEBUG");
 
+    m_killDeviceFrameCount = qEnvironmentVariableIntValue("QSG_RHI_SIMULATE_DEVICE_LOSS");
+    if (m_killDeviceFrameCount > 0 && m_rhiBackend == QRhi::D3D11)
+        qDebug("Graphics device will be reset every %d frames", m_killDeviceFrameCount);
+
     const char *backendName = "unknown";
     switch (m_rhiBackend) {
     case QRhi::Null:
@@ -489,6 +493,10 @@ QRhi *QSGRhiSupport::createRhi(QWindow *window, QOffscreenSurface *offscreenSurf
     if (backend == QRhi::D3D11) {
         QRhiD3D11InitParams rhiParams;
         rhiParams.enableDebugLayer = isDebugLayerRequested();
+        if (m_killDeviceFrameCount > 0) {
+            rhiParams.framesUntilKillingDeviceViaTdr = m_killDeviceFrameCount;
+            rhiParams.repeatDeviceKill = true;
+        }
         rhi = QRhi::create(backend, &rhiParams, flags);
     }
 #endif
diff --git a/src/quick/scenegraph/qsgrhisupport_p.h b/src/quick/scenegraph/qsgrhisupport_p.h
index f2d5837bba..536efa55c3 100644
--- a/src/quick/scenegraph/qsgrhisupport_p.h
+++ b/src/quick/scenegraph/qsgrhisupport_p.h
@@ -138,6 +138,7 @@ private:
         uint rhi : 1;
     } m_requested;
     QRhi::Implementation m_rhiBackend = QRhi::Null;
+    int m_killDeviceFrameCount;
     uint m_set : 1;
     uint m_enableRhi : 1;
     uint m_debugLayer : 1;