[PATCH 1/4 v2] dmaengine: add a tx_free method to structdma_async_tx_descriptor

[Guennadi Liakhovetski]

From: Guennadi Liakhovetski <lg@xxxxxxx>

Some users reuse DMA transaction descriptors multiple times and need an
explicit call to release them. An example of such a user is Video4Linux, which
has to be able to release descriptors on ioctl(VIDIOC_DQBUF).

Signed-off-by: Guennadi Liakhovetski <lg@xxxxxxx>
---
 include/linux/dmaengine.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 64dea2a..58b2268 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -183,6 +183,7 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param);
  *	descriptors
  * @chan: target channel for this operation
  * @tx_submit: set the prepared descriptor(s) to be executed by the engine
+ * @tx_free: release a transaction descriptor
  * @callback: routine to call after this operation is complete
  * @callback_param: general parameter to pass to the callback routine
  * ---async_tx api specific fields---
@@ -197,6 +198,7 @@ struct dma_async_tx_descriptor {
 	struct list_head tx_list;
 	struct dma_chan *chan;
 	dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
+	void (*tx_free)(struct dma_async_tx_descriptor *tx);
 	dma_async_tx_callback callback;
 	void *callback_param;
 	struct dma_async_tx_descriptor *next;
-- 
1.5.4

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