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Commit 078dec33 authored by Christian König's avatar Christian König
Browse files

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: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarChunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/265248/
parent 4fb86404

drivers/dma-buf/dma-fence.c

+35 −1
Original line number Diff line number Diff line
@@ -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

include/linux/dma-fence.h

+1 −0
Original line number Diff line number Diff line
@@ -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...) \