[PATCH 3/4] dma-buf: Add callback and enable signaling on debug

[Arvind Yadav <Arvind.Yadav@amd.com>]

Here's on debug adding an enable_signaling callback for the stub
fences and enabling software signaling for the stub fence which
is always signaled. This fence should enable software signaling
otherwise the AMD GPU scheduler will cause a GPU reset due to a
GPU scheduler cleanup activity timeout.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
---
 drivers/dma-buf/dma-fence.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 066400ed8841..0a67af945ef8 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -27,6 +27,10 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled);
 static DEFINE_SPINLOCK(dma_fence_stub_lock);
 static struct dma_fence dma_fence_stub;
 
+#ifdef CONFIG_DEBUG_FS
+static bool __dma_fence_enable_signaling(struct dma_fence *fence);
+#endif
+
 /*
  * fence context counter: each execution context should have its own
  * fence context, this allows checking if fences belong to the same
@@ -116,9 +120,19 @@ static const char *dma_fence_stub_get_name(struct dma_fence *fence)
         return "stub";
 }
 
+#ifdef CONFIG_DEBUG_FS
+static bool dma_fence_stub_enable_signaling(struct dma_fence *f)
+{
+	return true;
+}
+#endif
+
 static const struct dma_fence_ops dma_fence_stub_ops = {
 	.get_driver_name = dma_fence_stub_get_name,
 	.get_timeline_name = dma_fence_stub_get_name,
+#ifdef CONFIG_DEBUG_FS
+	.enable_signaling =  dma_fence_stub_enable_signaling,
+#endif
 };
 
 /**
@@ -136,6 +150,9 @@ struct dma_fence *dma_fence_get_stub(void)
 			       &dma_fence_stub_ops,
 			       &dma_fence_stub_lock,
 			       0, 0);
+#ifdef CONFIG_DEBUG_FS
+		__dma_fence_enable_signaling(&dma_fence_stub);
+#endif
 		dma_fence_signal_locked(&dma_fence_stub);
 	}
 	spin_unlock(&dma_fence_stub_lock);
-- 
2.25.1