[v2,36/41] dmaengine: add support to provide error result from a DMA transation

Commit Message

Dave Jiang July 15, 2016, 8:21 p.m. UTC

Adding a new callback that will provide the error result for a transaction.
The result is allocated on the stack and the callback should create a copy
if it wishes to retain the information after exiting.

Signed-off-by: Dave Jiang <[e-mail]>
---
 include/linux/dmaengine.h |   34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)


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Comments

Lars-Peter Clausen July 17, 2016, 6:49 p.m. UTC | #1

On 07/15/2016 10:21 PM, Dave Jiang wrote:
> +enum dmaengine_tx_result {
> +	DMA_TRANS_NOERROR = 0,
> +	DMA_TRANS_READ_FAILED,
> +	DMA_TRANS_WRITE_FAILED,
> +	DMA_TRANS_ABORTED,
> +};

There needs to be a very clear definition on the meaning and semantics of
each of these. Otherwise their meaning will become ambiguous over time and
clients have to fallback to heuristics to guess what the result actually means.

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Patch

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 95cf217..a43207e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -441,6 +441,21 @@  typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
 
 typedef void (*dma_async_tx_callback)(void *dma_async_param);
 
+enum dmaengine_tx_result {
+	DMA_TRANS_NOERROR = 0,
+	DMA_TRANS_READ_FAILED,
+	DMA_TRANS_WRITE_FAILED,
+	DMA_TRANS_ABORTED,
+};
+
+struct dmaengine_result {
+	enum dmaengine_tx_result result;
+	u32 residue;
+};
+
+typedef void (*dma_async_tx_callback_result)(void *dma_async_param,
+				const struct dmaengine_result *result);
+
 struct dmaengine_unmap_data {
 	u8 map_cnt;
 	u8 to_cnt;
@@ -478,6 +493,7 @@  struct dma_async_tx_descriptor {
 	dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
 	int (*desc_free)(struct dma_async_tx_descriptor *tx);
 	dma_async_tx_callback callback;
+	dma_async_tx_callback_result callback_result;
 	void *callback_param;
 	struct dmaengine_unmap_data *unmap;
 #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
@@ -1374,6 +1390,7 @@  static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 
 struct dmaengine_desc_callback {
 	dma_async_tx_callback callback;
+	dma_async_tx_callback_result callback_result;
 	void *callback_param;
 };
 
@@ -1382,15 +1399,26 @@  dmaengine_desc_get_callback(struct dma_async_tx_descriptor *tx,
 			    struct dmaengine_desc_callback *cb)
 {
 	cb->callback = tx->callback;
+	cb->callback_result = tx->callback_result;
 	cb->callback_param = tx->callback_param;
 }
 
 static inline void
 dmaengine_desc_callback_invoke(struct dmaengine_desc_callback *cb,
-			       void *result)
-{
-	if (cb->callback)
+			       struct dmaengine_result *result)
+{
+	struct dmaengine_result dummy_result = {
+		.result = DMA_TRANS_NOERROR,
+		.residue = 0
+	};
+
+	if (cb->callback_result) {
+		if (!result)
+			result = &dummy_result;
+		cb->callback_result(cb->callback_param, result);
+	} else if (cb->callback) {
 		cb->callback(cb->callback_param);
+	}
 }
 
 /* --- DMA device --- */