>From Documentation/crypto/async-tx-api.txt
"... Once a driver-specific threshold is met the driver
automatically issues pending operations. An application can force
this event by calling async_tx_issue_pending_all() ..."
That is, the DMA controller drivers may buffer transfer requests
for optimization. However it is perfectly legal to start dma as soon
as the user calls .tx_submit() on the descriptor, as the documentation
specifies in include/linux/dmaengine.h
It is also consistent with the expected behaviour. For example, if a
channel is already active when a client submits a request, we do not
expect the channel to stop after the current request is done and wait
for explicit issue_pending() from the user (the user has already done
prep() and submit()) on the last request.
Signed-off-by: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
---
drivers/dma/pl330.c | 24 ++++--------------------
1 file changed, 4 insertions(+), 20 deletions(-)
diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 19a9974..8ec5f1f 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -411,9 +411,7 @@ struct dma_pl330_chan {
/* DMA-Engine Channel */
struct dma_chan chan;
- /* List of submitted descriptors */
- struct list_head submitted_list;
- /* List of issued descriptors */
+ /* List of to be xfered descriptors */
struct list_head work_list;
/* List of completed descriptors */
struct list_head completed_list;
@@ -2084,11 +2082,6 @@ static int pl330_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned
pch->thread->req_running = -1;
/* 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);
@@ -2099,7 +2092,6 @@ 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, &pl330->desc_pool);
list_splice_tail_init(&pch->work_list, &pl330->desc_pool);
list_splice_tail_init(&pch->completed_list, &pl330->desc_pool);
spin_unlock_irqrestore(&pch->lock, flags);
@@ -2158,14 +2150,7 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
static void pl330_issue_pending(struct dma_chan *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);
+ pl330_tasklet((unsigned long) to_pchan(chan));
}
/*
@@ -2192,11 +2177,11 @@ static dma_cookie_t pl330_tx_submit(struct dma_async_tx_descriptor *tx)
dma_cookie_assign(&desc->txd);
- list_move_tail(&desc->node, &pch->submitted_list);
+ list_move_tail(&desc->node, &pch->work_list);
}
cookie = dma_cookie_assign(&last->txd);
- list_add_tail(&last->node, &pch->submitted_list);
+ list_add_tail(&last->node, &pch->work_list);
spin_unlock_irqrestore(&pch->lock, flags);
return cookie;
@@ -2680,7 +2665,6 @@ 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);
--
1.9.1
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