dma: pl330: Differentiate between submitted and issued descriptors

The pl330 dmaengine driver currently does not differentiate between submitted
and issued descriptors. It won't start transferring a newly submitted
descriptor until issue_pending() is called, but only if it is idle. If it is
active and a new descriptor is submitted before it goes idle it will happily
start the newly submitted descriptor once all earlier submitted descriptors have
been completed. This is not a 100% correct with regards to the dmaengine
interface semantics. A descriptor is not supposed to be started until the next
issue_pending() call after the descriptor has been submitted. This patch adds a
second per channel list that keeps track of the submitted descriptors. Once
issue_pending() is called the submitted descriptors are moved to the working
list and only descriptors on the working list are started.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 7adaf3abffba..8e018a221f19 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -543,7 +543,9 @@ struct dma_pl330_chan {
         /* DMA-Engine Channel */
         struct dma_chan chan;
 
-        /* List of to be xfered descriptors */
+        /* List of submitted descriptors */
+        struct list_head submitted_list;
+        /* List of issued descriptors */
         struct list_head work_list;
         /* List of completed descriptors */
         struct list_head completed_list;
@@ -2388,6 +2390,11 @@ static int pl330_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned
                 pl330_chan_ctrl(pch->pl330_chid, PL330_OP_FLUSH);
 
                 /* Mark all desc done */
+                list_for_each_entry(desc, &pch->submitted_list, node) {
+                        desc->status = FREE;
+                        dma_cookie_complete(&desc->txd);
+                }
+
                 list_for_each_entry(desc, &pch->work_list , node) {
                         desc->status = FREE;
                         dma_cookie_complete(&desc->txd);
@@ -2398,6 +2405,7 @@ static int pl330_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned
                         dma_cookie_complete(&desc->txd);
                 }
 
+                list_splice_tail_init(&pch->submitted_list, &pdmac->desc_pool);
                 list_splice_tail_init(&pch->work_list, &pdmac->desc_pool);
                 list_splice_tail_init(&pch->completed_list, &pdmac->desc_pool);
                 spin_unlock_irqrestore(&pch->lock, flags);
@@ -2456,7 +2464,14 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
 
 static void pl330_issue_pending(struct dma_chan *chan)
 {
-        pl330_tasklet((unsigned long) to_pchan(chan));
+        struct dma_pl330_chan *pch = to_pchan(chan);
+        unsigned long flags;
+
+        spin_lock_irqsave(&pch->lock, flags);
+        list_splice_tail_init(&pch->submitted_list, &pch->work_list);
+        spin_unlock_irqrestore(&pch->lock, flags);
+
+        pl330_tasklet((unsigned long)pch);
 }
 
 /*
@@ -2483,11 +2498,11 @@ static dma_cookie_t pl330_tx_submit(struct dma_async_tx_descriptor *tx)
 
                 dma_cookie_assign(&desc->txd);
 
-                list_move_tail(&desc->node, &pch->work_list);
+                list_move_tail(&desc->node, &pch->submitted_list);
         }
 
         cookie = dma_cookie_assign(&last->txd);
-        list_add_tail(&last->node, &pch->work_list);
+        list_add_tail(&last->node, &pch->submitted_list);
         spin_unlock_irqrestore(&pch->lock, flags);
 
         return cookie;
@@ -2979,6 +2994,7 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
                 else
                         pch->chan.private = adev->dev.of_node;
 
+                INIT_LIST_HEAD(&pch->submitted_list);
                 INIT_LIST_HEAD(&pch->work_list);
                 INIT_LIST_HEAD(&pch->completed_list);
                 spin_lock_init(&pch->lock);