dmaengine: ack to flags: make use of the unused bits in the 'ack' field

'ack' is currently a simple integer that flags whether or not a client is done
touching fields in the given descriptor.  It is effectively just a single bit
of information.  Converting this to a flags parameter allows the other bits to
be put to use to control completion actions, like dma-unmap, and capture
results, like xor-zero-sum == 0.

Changes are one of:
1/ convert all open-coded ->ack manipulations to use async_tx_ack
   and async_tx_test_ack.
2/ set the ack bit at prep time where possible
3/ make drivers store the flags at prep time
4/ add flags to the device_prep_dma_interrupt prototype

Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

8 files changed, 69 insertions, 54 deletions

diff --git a/crypto/async_tx/async_memcpy.c b/crypto/async_tx/async_memcpy.c
index 84caa4efc0d4..a5eda80e8427 100644
--- a/crypto/async_tx/async_memcpy.c
+++ b/crypto/async_tx/async_memcpy.c
@@ -77,7 +77,7 @@ async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
                         /* if ack is already set then we cannot be sure
                          * we are referring to the correct operation
                          */
-                        BUG_ON(depend_tx->ack);
+                        BUG_ON(async_tx_test_ack(depend_tx));
                         if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
                                 panic("%s: DMA_ERROR waiting for depend_tx\n",
                                         __func__);
diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c
index 69756164b61d..c6e772fc5ccd 100644
--- a/crypto/async_tx/async_tx.c
+++ b/crypto/async_tx/async_tx.c
@@ -446,7 +446,7 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
          * otherwise poll for completion
          */
         if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
-                intr_tx = device->device_prep_dma_interrupt(chan);
+                intr_tx = device->device_prep_dma_interrupt(chan, 0);
         else
                 intr_tx = NULL;
 
@@ -515,7 +515,8 @@ async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
                  * 2/ dependencies are 1:1 i.e. two transactions can
                  * not depend on the same parent
                  */
-                BUG_ON(depend_tx->ack || depend_tx->next || tx->parent);
+                BUG_ON(async_tx_test_ack(depend_tx) || depend_tx->next ||
+                       tx->parent);
 
                 /* the lock prevents async_tx_run_dependencies from missing
                  * the setting of ->next when ->parent != NULL
@@ -594,7 +595,7 @@ async_trigger_callback(enum async_tx_flags flags,
                 if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
                         device = NULL;
 
-                tx = device ? device->device_prep_dma_interrupt(chan) : NULL;
+                tx = device ? device->device_prep_dma_interrupt(chan, 0) : NULL;
         } else
                 tx = NULL;
 
@@ -610,7 +611,7 @@ async_trigger_callback(enum async_tx_flags flags,
                         /* if ack is already set then we cannot be sure
                          * we are referring to the correct operation
                          */
-                        BUG_ON(depend_tx->ack);
+                        BUG_ON(async_tx_test_ack(depend_tx));
                         if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
                                 panic("%s: DMA_ERROR waiting for depend_tx\n",
                                         __func__);
diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
index 1c445c7bdab7..3a0dddca5a10 100644
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -191,7 +191,7 @@ async_xor(struct page *dest, struct page **src_list, unsigned int offset,
                                 /* if ack is already set then we cannot be sure
                                  * we are referring to the correct operation
                                  */
-                                BUG_ON(depend_tx->ack);
+                                BUG_ON(async_tx_test_ack(depend_tx));
                                 if (dma_wait_for_async_tx(depend_tx) ==
                                         DMA_ERROR)
                                         panic("%s: DMA_ERROR waiting for "
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index af6911a75dae..d6dc70fd7527 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -478,7 +478,8 @@ dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
 
         dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
         dma_dest = dma_map_single(dev->dev, dest, len, DMA_FROM_DEVICE);
-        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
+        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
+                                         DMA_CTRL_ACK);
 
         if (!tx) {
                 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
@@ -486,7 +487,6 @@ dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
                 return -ENOMEM;
         }
 
-        tx->ack = 1;
         tx->callback = NULL;
         cookie = tx->tx_submit(tx);
 
@@ -524,7 +524,8 @@ dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
 
         dma_src = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
         dma_dest = dma_map_page(dev->dev, page, offset, len, DMA_FROM_DEVICE);
-        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
+        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
+                                         DMA_CTRL_ACK);
 
         if (!tx) {
                 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
@@ -532,7 +533,6 @@ dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
                 return -ENOMEM;
         }
 
-        tx->ack = 1;
         tx->callback = NULL;
         cookie = tx->tx_submit(tx);
 
@@ -573,7 +573,8 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
         dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
         dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
                                 DMA_FROM_DEVICE);
-        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
+        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
+                                         DMA_CTRL_ACK);
 
         if (!tx) {
                 dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
@@ -581,7 +582,6 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
                 return -ENOMEM;
         }
 
-        tx->ack = 1;
         tx->callback = NULL;
         cookie = tx->tx_submit(tx);
 
diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 95b36b7934a5..054eabffc185 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -412,7 +412,7 @@ static void fsl_dma_free_chan_resources(struct dma_chan *chan)
 }
 
 static struct dma_async_tx_descriptor *
-fsl_dma_prep_interrupt(struct dma_chan *chan)
+fsl_dma_prep_interrupt(struct dma_chan *chan, unsigned long flags)
 {
         struct fsl_dma_chan *fsl_chan;
         struct fsl_desc_sw *new;
@@ -429,7 +429,7 @@ fsl_dma_prep_interrupt(struct dma_chan *chan)
         }
 
         new->async_tx.cookie = -EBUSY;
-        new->async_tx.ack = 0;
+        new->async_tx.flags = flags;
 
         /* Insert the link descriptor to the LD ring */
         list_add_tail(&new->node, &new->async_tx.tx_list);
@@ -482,7 +482,7 @@ static struct dma_async_tx_descriptor *fsl_dma_prep_memcpy(
                         set_desc_next(fsl_chan, &prev->hw, new->async_tx.phys);
 
                 new->async_tx.cookie = 0;
-                new->async_tx.ack = 1;
+                async_tx_ack(&new->async_tx);
 
                 prev = new;
                 len -= copy;
@@ -493,7 +493,7 @@ static struct dma_async_tx_descriptor *fsl_dma_prep_memcpy(
                 list_add_tail(&new->node, &first->async_tx.tx_list);
         } while (len);
 
-        new->async_tx.ack = 0; /* client is in control of this ack */
+        new->async_tx.flags = flags; /* client is in control of this ack */
         new->async_tx.cookie = -EBUSY;
 
         /* Set End-of-link to the last link descriptor of new list*/
@@ -874,7 +874,7 @@ static int fsl_dma_self_test(struct fsl_dma_chan *fsl_chan)
         async_tx_ack(tx3);
 
         /* Interrupt tx test */
-        tx1 = fsl_dma_prep_interrupt(chan);
+        tx1 = fsl_dma_prep_interrupt(chan, 0);
         async_tx_ack(tx1);
         cookie = fsl_dma_tx_submit(tx1);
 
diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index 1517fe4e2d14..318e8a22d814 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -212,14 +212,14 @@ static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
         u32 copy;
         size_t len;
         dma_addr_t src, dst;
-        int orig_ack;
+        unsigned long orig_flags;
         unsigned int desc_count = 0;
 
         /* src and dest and len are stored in the initial descriptor */
         len = first->len;
         src = first->src;
         dst = first->dst;
-        orig_ack = first->async_tx.ack;
+        orig_flags = first->async_tx.flags;
         new = first;
 
         spin_lock_bh(&ioat_chan->desc_lock);
@@ -228,7 +228,7 @@ static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
         do {
                 copy = min_t(size_t, len, ioat_chan->xfercap);
 
-                new->async_tx.ack = 1;
+                async_tx_ack(&new->async_tx);
 
                 hw = new->hw;
                 hw->size = copy;
@@ -264,7 +264,7 @@ static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
         }
 
         new->tx_cnt = desc_count;
-        new->async_tx.ack = orig_ack; /* client is in control of this ack */
+        new->async_tx.flags = orig_flags; /* client is in control of this ack */
 
         /* store the original values for use in later cleanup */
         if (new != first) {
@@ -304,14 +304,14 @@ static dma_cookie_t ioat2_tx_submit(struct dma_async_tx_descriptor *tx)
         u32 copy;
         size_t len;
         dma_addr_t src, dst;
-        int orig_ack;
+        unsigned long orig_flags;
         unsigned int desc_count = 0;
 
         /* src and dest and len are stored in the initial descriptor */
         len = first->len;
         src = first->src;
         dst = first->dst;
-        orig_ack = first->async_tx.ack;
+        orig_flags = first->async_tx.flags;
         new = first;
 
         /*
@@ -321,7 +321,7 @@ static dma_cookie_t ioat2_tx_submit(struct dma_async_tx_descriptor *tx)
         do {
                 copy = min_t(size_t, len, ioat_chan->xfercap);
 
-                new->async_tx.ack = 1;
+                async_tx_ack(&new->async_tx);
 
                 hw = new->hw;
                 hw->size = copy;
@@ -349,7 +349,7 @@ static dma_cookie_t ioat2_tx_submit(struct dma_async_tx_descriptor *tx)
         }
 
         new->tx_cnt = desc_count;
-        new->async_tx.ack = orig_ack; /* client is in control of this ack */
+        new->async_tx.flags = orig_flags; /* client is in control of this ack */
 
         /* store the original values for use in later cleanup */
         if (new != first) {
@@ -714,7 +714,7 @@ static struct dma_async_tx_descriptor *ioat1_dma_prep_memcpy(
                 new->len = len;
                 new->dst = dma_dest;
                 new->src = dma_src;
-                new->async_tx.ack = 0;
+                new->async_tx.flags = flags;
                 return &new->async_tx;
         } else
                 return NULL;
@@ -742,7 +742,7 @@ static struct dma_async_tx_descriptor *ioat2_dma_prep_memcpy(
                 new->len = len;
                 new->dst = dma_dest;
                 new->src = dma_src;
-                new->async_tx.ack = 0;
+                new->async_tx.flags = flags;
                 return &new->async_tx;
         } else
                 return NULL;
@@ -842,7 +842,7 @@ static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan)
                                  * a completed entry, but not the last, so clean
                                  * up if the client is done with the descriptor
                                  */
-                                if (desc->async_tx.ack) {
+                                if (async_tx_test_ack(&desc->async_tx)) {
                                         list_del(&desc->node);
                                         list_add_tail(&desc->node,
                                                       &ioat_chan->free_desc);
@@ -979,7 +979,7 @@ static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan)
         desc->hw->size = 0;
         desc->hw->src_addr = 0;
         desc->hw->dst_addr = 0;
-        desc->async_tx.ack = 1;
+        async_tx_ack(&desc->async_tx);
         switch (ioat_chan->device->version) {
         case IOAT_VER_1_2:
                 desc->hw->next = 0;
diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c
index 93252294f32b..762b729672e0 100644
--- a/drivers/dma/iop-adma.c
+++ b/drivers/dma/iop-adma.c
@@ -111,7 +111,7 @@ iop_adma_clean_slot(struct iop_adma_desc_slot *desc,
         /* the client is allowed to attach dependent operations
          * until 'ack' is set
          */
-        if (!desc->async_tx.ack)
+        if (!async_tx_test_ack(&desc->async_tx))
                 return 0;
 
         /* leave the last descriptor in the chain
@@ -148,7 +148,7 @@ static void __iop_adma_slot_cleanup(struct iop_adma_chan *iop_chan)
                         "this_desc: %#x next_desc: %#x ack: %d\n",
                         iter->async_tx.cookie, iter->idx, busy,
                         iter->async_tx.phys, iop_desc_get_next_desc(iter),
-                        iter->async_tx.ack);
+                        async_tx_test_ack(&iter->async_tx));
                 prefetch(_iter);
                 prefetch(&_iter->async_tx);
 
@@ -338,9 +338,7 @@ retry:
 
                                 /* pre-ack all but the last descriptor */
                                 if (num_slots != slots_per_op)
-                                        iter->async_tx.ack = 1;
-                                else
-                                        iter->async_tx.ack = 0;
+                                        async_tx_ack(&iter->async_tx);
 
                                 list_add_tail(&iter->chain_node, &chain);
                                 alloc_tail = iter;
@@ -513,7 +511,7 @@ static int iop_adma_alloc_chan_resources(struct dma_chan *chan)
 }
 
 static struct dma_async_tx_descriptor *
-iop_adma_prep_dma_interrupt(struct dma_chan *chan)
+iop_adma_prep_dma_interrupt(struct dma_chan *chan, unsigned long flags)
 {
         struct iop_adma_chan *iop_chan = to_iop_adma_chan(chan);
         struct iop_adma_desc_slot *sw_desc, *grp_start;
@@ -528,6 +526,7 @@ iop_adma_prep_dma_interrupt(struct dma_chan *chan)
                 grp_start = sw_desc->group_head;
                 iop_desc_init_interrupt(grp_start, iop_chan);
                 grp_start->unmap_len = 0;
+                sw_desc->async_tx.flags = flags;
         }
         spin_unlock_bh(&iop_chan->lock);
 
@@ -560,6 +559,7 @@ iop_adma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dma_dest,
                 iop_desc_set_memcpy_src_addr(grp_start, dma_src);
                 sw_desc->unmap_src_cnt = 1;
                 sw_desc->unmap_len = len;
+                sw_desc->async_tx.flags = flags;
         }
         spin_unlock_bh(&iop_chan->lock);
 
@@ -592,6 +592,7 @@ iop_adma_prep_dma_memset(struct dma_chan *chan, dma_addr_t dma_dest,
                 iop_desc_set_dest_addr(grp_start, iop_chan, dma_dest);
                 sw_desc->unmap_src_cnt = 1;
                 sw_desc->unmap_len = len;
+                sw_desc->async_tx.flags = flags;
         }
         spin_unlock_bh(&iop_chan->lock);
 
@@ -625,6 +626,7 @@ iop_adma_prep_dma_xor(struct dma_chan *chan, dma_addr_t dma_dest,
                 iop_desc_set_dest_addr(grp_start, iop_chan, dma_dest);
                 sw_desc->unmap_src_cnt = src_cnt;
                 sw_desc->unmap_len = len;
+                sw_desc->async_tx.flags = flags;
                 while (src_cnt--)
                         iop_desc_set_xor_src_addr(grp_start, src_cnt,
                                                   dma_src[src_cnt]);
@@ -661,6 +663,7 @@ iop_adma_prep_dma_zero_sum(struct dma_chan *chan, dma_addr_t *dma_src,
                         __func__, grp_start->xor_check_result);
                 sw_desc->unmap_src_cnt = src_cnt;
                 sw_desc->unmap_len = len;
+                sw_desc->async_tx.flags = flags;
                 while (src_cnt--)
                         iop_desc_set_zero_sum_src_addr(grp_start, src_cnt,
                                                        dma_src[src_cnt]);
@@ -847,11 +850,11 @@ static int __devinit iop_adma_memcpy_self_test(struct iop_adma_device *device)
         src_dma = dma_map_single(dma_chan->device->dev, src,
                                 IOP_ADMA_TEST_SIZE, DMA_TO_DEVICE);
         tx = iop_adma_prep_dma_memcpy(dma_chan, dest_dma, src_dma,
-                                      IOP_ADMA_TEST_SIZE, 1);
+                                      IOP_ADMA_TEST_SIZE,
+                                      DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
         cookie = iop_adma_tx_submit(tx);
         iop_adma_issue_pending(dma_chan);
-        async_tx_ack(tx);
         msleep(1);
 
         if (iop_adma_is_complete(dma_chan, cookie, NULL, NULL) !=
@@ -947,11 +950,11 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
                 dma_srcs[i] = dma_map_page(dma_chan->device->dev, xor_srcs[i],
                                            0, PAGE_SIZE, DMA_TO_DEVICE);
         tx = iop_adma_prep_dma_xor(dma_chan, dest_dma, dma_srcs,
-                                   IOP_ADMA_NUM_SRC_TEST, PAGE_SIZE, 1);
+                                   IOP_ADMA_NUM_SRC_TEST, PAGE_SIZE,
+                                   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
         cookie = iop_adma_tx_submit(tx);
         iop_adma_issue_pending(dma_chan);
-        async_tx_ack(tx);
         msleep(8);
 
         if (iop_adma_is_complete(dma_chan, cookie, NULL, NULL) !=
@@ -994,11 +997,11 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
                                            DMA_TO_DEVICE);
         tx = iop_adma_prep_dma_zero_sum(dma_chan, dma_srcs,
                                         IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
-                                        &zero_sum_result, 1);
+                                        &zero_sum_result,
+                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
         cookie = iop_adma_tx_submit(tx);
         iop_adma_issue_pending(dma_chan);
-        async_tx_ack(tx);
         msleep(8);
 
         if (iop_adma_is_complete(dma_chan, cookie, NULL, NULL) != DMA_SUCCESS) {
@@ -1018,11 +1021,11 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
         /* test memset */
         dma_addr = dma_map_page(dma_chan->device->dev, dest, 0,
                         PAGE_SIZE, DMA_FROM_DEVICE);
-        tx = iop_adma_prep_dma_memset(dma_chan, dma_addr, 0, PAGE_SIZE, 1);
+        tx = iop_adma_prep_dma_memset(dma_chan, dma_addr, 0, PAGE_SIZE,
+                                      DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
         cookie = iop_adma_tx_submit(tx);
         iop_adma_issue_pending(dma_chan);
-        async_tx_ack(tx);
         msleep(8);
 
         if (iop_adma_is_complete(dma_chan, cookie, NULL, NULL) != DMA_SUCCESS) {
@@ -1050,11 +1053,11 @@ iop_adma_xor_zero_sum_self_test(struct iop_adma_device *device)
                                            DMA_TO_DEVICE);
         tx = iop_adma_prep_dma_zero_sum(dma_chan, dma_srcs,
                                         IOP_ADMA_NUM_SRC_TEST + 1, PAGE_SIZE,
-                                        &zero_sum_result, 1);
+                                        &zero_sum_result,
+                                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
         cookie = iop_adma_tx_submit(tx);
         iop_adma_issue_pending(dma_chan);
-        async_tx_ack(tx);
         msleep(8);
 
         if (iop_adma_is_complete(dma_chan, cookie, NULL, NULL) != DMA_SUCCESS) {
@@ -1287,7 +1290,7 @@ static void iop_chan_start_null_memcpy(struct iop_adma_chan *iop_chan)
                 grp_start = sw_desc->group_head;
 
                 list_splice_init(&sw_desc->async_tx.tx_list, &iop_chan->chain);
-                sw_desc->async_tx.ack = 1;
+                async_tx_ack(&sw_desc->async_tx);
                 iop_desc_init_memcpy(grp_start, 0);
                 iop_desc_set_byte_count(grp_start, iop_chan, 0);
                 iop_desc_set_dest_addr(grp_start, iop_chan, 0);
@@ -1343,7 +1346,7 @@ static void iop_chan_start_null_xor(struct iop_adma_chan *iop_chan)
         if (sw_desc) {
                 grp_start = sw_desc->group_head;
                 list_splice_init(&sw_desc->async_tx.tx_list, &iop_chan->chain);
-                sw_desc->async_tx.ack = 1;
+                async_tx_ack(&sw_desc->async_tx);
                 iop_desc_init_null_xor(grp_start, 2, 0);
                 iop_desc_set_byte_count(grp_start, iop_chan, 0);
                 iop_desc_set_dest_addr(grp_start, iop_chan, 0);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index cd34df78c6aa..b4d84ed6187d 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -95,12 +95,17 @@ enum dma_transaction_type {
 #define DMA_TX_TYPE_END (DMA_INTERRUPT + 1)
 
 /**
- * enum dma_prep_flags - DMA flags to augment operation preparation
+ * enum dma_ctrl_flags - DMA flags to augment operation preparation,
+ *      control completion, and communicate status.
  * @DMA_PREP_INTERRUPT - trigger an interrupt (callback) upon completion of
  *      this transaction
+ * @DMA_CTRL_ACK - the descriptor cannot be reused until the client
+ *      acknowledges receipt, i.e. has has a chance to establish any
+ *      dependency chains
  */
-enum dma_prep_flags {
+enum dma_ctrl_flags {
         DMA_PREP_INTERRUPT = (1 << 0),
+        DMA_CTRL_ACK = (1 << 1),
 };
 
 /**
@@ -211,8 +216,8 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param);
  * ---dma generic offload fields---
  * @cookie: tracking cookie for this transaction, set to -EBUSY if
  *      this tx is sitting on a dependency list
- * @ack: the descriptor can not be reused until the client acknowledges
- *      receipt, i.e. has has a chance to establish any dependency chains
+ * @flags: flags to augment operation preparation, control completion, and
+ *      communicate status
  * @phys: physical address of the descriptor
  * @tx_list: driver common field for operations that require multiple
  *      descriptors
@@ -227,7 +232,7 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param);
  */
 struct dma_async_tx_descriptor {
         dma_cookie_t cookie;
-        int ack;
+        enum dma_ctrl_flags flags; /* not a 'long' to pack with cookie */
         dma_addr_t phys;
         struct list_head tx_list;
         struct dma_chan *chan;
@@ -290,7 +295,7 @@ struct dma_device {
                 struct dma_chan *chan, dma_addr_t dest, int value, size_t len,
                 unsigned long flags);
         struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
-                struct dma_chan *chan);
+                struct dma_chan *chan, unsigned long flags);
 
         enum dma_status (*device_is_tx_complete)(struct dma_chan *chan,
                         dma_cookie_t cookie, dma_cookie_t *last,
@@ -316,7 +321,13 @@ void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
 static inline void
 async_tx_ack(struct dma_async_tx_descriptor *tx)
 {
-        tx->ack = 1;
+        tx->flags |= DMA_CTRL_ACK;
+}
+
+static inline int
+async_tx_test_ack(struct dma_async_tx_descriptor *tx)
+{
+        return tx->flags & DMA_CTRL_ACK;
 }
 
 #define first_dma_cap(mask) __first_dma_cap(&(mask))