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>

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 7adaf3abffba91d4f72656513c6ad5b235508c40..8e018a221f19037fe90f3e0a61f9c1daff4f7d2f 100644 (file)
--- 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);