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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/
hifive-unleashed-5.1
Christian König 2018-12-03 13:36:14 +01:00
parent 4fb86404a9
commit 078dec3326
2 changed files with 36 additions and 1 deletions
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36
drivers/dma-buf/dma-fence.c
View File

@ -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

1
include/linux/dma-fence.h
View File

@ -541,6 +541,7 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
return ret < 0 ? ret : 0;
}
struct dma_fence *dma_fence_get_stub(void);
u64 dma_fence_context_alloc(unsigned num);
#define DMA_FENCE_TRACE(f, fmt, args...) \