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authorChristian König <christian.koenig@amd.com>2018-12-03 15:36:14 +0300
committerChristian König <christian.koenig@amd.com>2018-12-03 19:40:18 +0300
commit078dec3326e2244c62e8a8d970ba24359e3464be (patch)
treefe94d4a9b88eac3915cdc1eaa5f560a517bd2abe /drivers/dma-buf/dma-fence.c
parent4fb86404a977b932eed56c0dd0954f6225eee3eb (diff)
downloadlinux-078dec3326e2244c62e8a8d970ba24359e3464be.tar.xz
dma-buf: add dma_fence_get_stub
Extract of useful code from the timeline work. This provides a function to return a stub or dummy fence which is always signaled. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chunming Zhou <david1.zhou@amd.com> Link: https://patchwork.freedesktop.org/patch/265248/
Diffstat (limited to 'drivers/dma-buf/dma-fence.c')
-rw-r--r--drivers/dma-buf/dma-fence.c36
1 files changed, 35 insertions, 1 deletions
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 1551ca7df394..136ec04d683f 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -30,13 +30,16 @@
EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
+static DEFINE_SPINLOCK(dma_fence_stub_lock);
+static struct dma_fence dma_fence_stub;
+
/*
* fence context counter: each execution context should have its own
* fence context, this allows checking if fences belong to the same
* context or not. One device can have multiple separate contexts,
* and they're used if some engine can run independently of another.
*/
-static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
+static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(1);
/**
* DOC: DMA fences overview
@@ -68,6 +71,37 @@ static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
* &dma_buf.resv pointer.
*/
+static const char *dma_fence_stub_get_name(struct dma_fence *fence)
+{
+ return "stub";
+}
+
+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,
+};
+
+/**
+ * dma_fence_get_stub - return a signaled fence
+ *
+ * Return a stub fence which is already signaled.
+ */
+struct dma_fence *dma_fence_get_stub(void)
+{
+ spin_lock(&dma_fence_stub_lock);
+ if (!dma_fence_stub.ops) {
+ dma_fence_init(&dma_fence_stub,
+ &dma_fence_stub_ops,
+ &dma_fence_stub_lock,
+ 0, 0);
+ dma_fence_signal_locked(&dma_fence_stub);
+ }
+ spin_unlock(&dma_fence_stub_lock);
+
+ return dma_fence_get(&dma_fence_stub);
+}
+EXPORT_SYMBOL(dma_fence_get_stub);
+
/**
* dma_fence_context_alloc - allocate an array of fence contexts
* @num: amount of contexts to allocate