async_tx: fix multiple dependency submission

Shrink struct dma_async_tx_descriptor and introduce
async_tx_channel_switch to properly inject a channel switch interrupt in
the descriptor stream.  This simplifies the locking model as drivers no
longer need to handle dma_async_tx_descriptor.lock.

Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 5 insertions, 6 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 8db0e7f9d3f4..9cb898a76bb3 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -600,8 +600,6 @@ void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
 {
         tx->chan = chan;
         spin_lock_init(&tx->lock);
-        INIT_LIST_HEAD(&tx->depend_node);
-        INIT_LIST_HEAD(&tx->depend_list);
 }
 EXPORT_SYMBOL(dma_async_tx_descriptor_init);
 
diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c
index f82b0906d466..21854cd7190f 100644
--- a/drivers/dma/iop-adma.c
+++ b/drivers/dma/iop-adma.c
@@ -63,7 +63,6 @@ iop_adma_run_tx_complete_actions(struct iop_adma_desc_slot *desc,
         struct iop_adma_chan *iop_chan, dma_cookie_t cookie)
 {
         BUG_ON(desc->async_tx.cookie < 0);
-        spin_lock_bh(&desc->async_tx.lock);
         if (desc->async_tx.cookie > 0) {
                 cookie = desc->async_tx.cookie;
                 desc->async_tx.cookie = 0;
@@ -101,7 +100,6 @@ iop_adma_run_tx_complete_actions(struct iop_adma_desc_slot *desc,
 
         /* run dependent operations */
         async_tx_run_dependencies(&desc->async_tx);
-        spin_unlock_bh(&desc->async_tx.lock);
 
         return cookie;
 }
@@ -275,8 +273,11 @@ iop_adma_slot_cleanup(struct iop_adma_chan *iop_chan)
 
 static void iop_adma_tasklet(unsigned long data)
 {
-        struct iop_adma_chan *chan = (struct iop_adma_chan *) data;
-        __iop_adma_slot_cleanup(chan);
+        struct iop_adma_chan *iop_chan = (struct iop_adma_chan *) data;
+
+        spin_lock(&iop_chan->lock);
+        __iop_adma_slot_cleanup(iop_chan);
+        spin_unlock(&iop_chan->lock);
 }
 
 static struct iop_adma_desc_slot *