[PATCH v2 1/2] dmaengine: dw-edma: Fix to change for continuous transfer

Shunsuke Mie
2023-04-11T10:18:08Z

The dw-edma driver stops after processing a DMA request even if a request
remains in the issued queue, which is not the expected behavior. The DMA
engine API requires continuous processing.

Add a trigger to start after one processing finished if there are requests
remain.

Fixes: e63d79d1ffcd ("dmaengine: Add Synopsys eDMA IP core driver")
Signed-off-by: Shunsuke Mie <mie@igel.co.jp>
---
Changes

v2:
- Refactor code
- Rebase to next-20230411

v1: https://lore.kernel.org/dmaengine/20221223022608.550697-1-mie@igel.co.jp/
- Initial patch

drivers/dma/dw-edma/dw-edma-core.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 1906a836f0aa..26a395d02f5d 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -181,7 +181,7 @@ static void vchan_free_desc(struct virt_dma_desc *vdesc)
dw_edma_free_desc(vd2dw_edma_desc(vdesc));
}

-static void dw_edma_start_transfer(struct dw_edma_chan *chan)
+static int dw_edma_start_transfer(struct dw_edma_chan *chan)
{
struct dw_edma_chunk *child;
struct dw_edma_desc *desc;
@@ -189,16 +189,16 @@ static void dw_edma_start_transfer(struct dw_edma_chan *chan)

vd = vchan_next_desc(&chan->vc);
if (!vd)
- return;
+ return 0;

desc = vd2dw_edma_desc(vd);
if (!desc)
- return;
+ return 0;

child = list_first_entry_or_null(&desc->chunk->list,
struct dw_edma_chunk, list);
if (!child)
- return;
+ return 0;

dw_edma_v0_core_start(child, !desc->xfer_sz);
desc->xfer_sz += child->ll_region.sz;
@@ -206,6 +206,8 @@ static void dw_edma_start_transfer(struct dw_edma_chan *chan)
list_del(&child->list);
kfree(child);
desc->chunks_alloc--;
+
+ return 1;
}

static void dw_edma_device_caps(struct dma_chan *dchan,
@@ -602,14 +604,14 @@ static void dw_edma_done_interrupt(struct dw_edma_chan *chan)
switch (chan->request) {
case EDMA_REQ_NONE:
desc = vd2dw_edma_desc(vd);
- if (desc->chunks_alloc) {
- chan->status = EDMA_ST_BUSY;
- dw_edma_start_transfer(chan);
- } else {
+ if (!desc->chunks_alloc) {
list_del(&vd->node);
vchan_cookie_complete(vd);
- chan->status = EDMA_ST_IDLE;
}
+
+ /* Continue transferring if there are remaining chunks or issued requests.
+ */
+ chan->status = dw_edma_start_transfer(chan) ? EDMA_ST_BUSY : EDMA_ST_IDLE;
break;

case EDMA_REQ_STOP:
--
2.25.1