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authorDan Williams <dan.j.williams@intel.com>2009-09-08 17:42:50 -0700
committerDan Williams <dan.j.williams@intel.com>2009-09-08 17:42:50 -0700
commit0403e3827788d878163f9ef0541b748b0f88ca5d (patch)
tree2dc73744bd92c268a1310f24668167f130877278 /crypto/async_tx/async_pq.c
parentf9dd2134374c8de6b911e2b8652c6c9622eaa658 (diff)
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dmaengine: add fence support
Some engines optimize operation by reading ahead in the descriptor chain such that descriptor2 may start execution before descriptor1 completes. If descriptor2 depends on the result from descriptor1 then a fence is required (on descriptor2) to disable this optimization. The async_tx api could implicitly identify dependencies via the 'depend_tx' parameter, but that would constrain cases where the dependency chain only specifies a completion order rather than a data dependency. So, provide an ASYNC_TX_FENCE to explicitly identify data dependencies. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'crypto/async_tx/async_pq.c')
-rw-r--r--crypto/async_tx/async_pq.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
index 108b21efb49..a25e290c39f 100644
--- a/crypto/async_tx/async_pq.c
+++ b/crypto/async_tx/async_pq.c
@@ -101,6 +101,7 @@ do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
*/
if (src_cnt > pq_src_cnt) {
submit->flags &= ~ASYNC_TX_ACK;
+ submit->flags |= ASYNC_TX_FENCE;
dma_flags |= DMA_COMPL_SKIP_DEST_UNMAP;
submit->cb_fn = NULL;
submit->cb_param = NULL;
@@ -111,6 +112,8 @@ do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
if (cb_fn_orig)
dma_flags |= DMA_PREP_INTERRUPT;
}
+ if (submit->flags & ASYNC_TX_FENCE)
+ dma_flags |= DMA_PREP_FENCE;
/* Since we have clobbered the src_list we are committed
* to doing this asynchronously. Drivers force forward
@@ -282,6 +285,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
dma_flags |= DMA_PREP_PQ_DISABLE_P;
if (!Q(blocks, disks))
dma_flags |= DMA_PREP_PQ_DISABLE_Q;
+ if (submit->flags & ASYNC_TX_FENCE)
+ dma_flags |= DMA_PREP_FENCE;
for (i = 0; i < disks; i++)
if (likely(blocks[i])) {
BUG_ON(is_raid6_zero_block(blocks[i]));