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* [PATCH v2 1/1] ntb: use dmaengine_get_dma_device() instead of chan->device->dev
@ 2026-09-21 20:39 Frank.Li
  2026-09-21 23:09 ` Dave Jiang
  0 siblings, 1 reply; 2+ messages in thread
From: Frank.Li @ 2026-09-21 20:39 UTC (permalink / raw)
  To: Jon Mason, Dave Jiang, Allen Hubbe, Frank Li,
	open list:NTB DRIVER CORE, open list
  Cc: imx, vkoul

From: Frank Li <Frank.Li@nxp.com>

Replace direct dma_chan::device::dev access with the proper
dmaengine_get_dma_device() accessor in NTB DMA consumers.

chan->device->dev is not always the device used for DMA mapping.
Some DMA engines support per-channel IOMMU mappings, so different
channels may use different DMA devices.  dmaengine_get_dma_device()
returns the correct device for each channel.

This also prepares for making the DMA engine provider data structures
private. DMA consumers should not access DMA engine internals directly.

Assisted-by: LLM
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change in v2
- fix commit message wrong mention IIO (copy-parste error). (report by
sashkio)
---
 drivers/ntb/ntb_transport.c | 29 +++++++++++++++++------------
 drivers/ntb/test/ntb_perf.c | 14 ++++++++------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index f9caa1a653c5b..890697cfc6b96 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1519,6 +1519,7 @@ static int ntb_async_rx_submit(struct ntb_queue_entry *entry, void *offset)
 	struct ntb_transport_qp *qp = entry->qp;
 	struct dma_chan *chan = qp->rx_dma_chan;
 	struct dma_device *device;
+	struct device *dma_dev;
 	size_t pay_off, buff_off, len;
 	struct dmaengine_unmap_data *unmap;
 	dma_cookie_t cookie;
@@ -1526,27 +1527,28 @@ static int ntb_async_rx_submit(struct ntb_queue_entry *entry, void *offset)
 
 	len = entry->len;
 	device = chan->device;
+	dma_dev = dmaengine_get_dma_device(chan);
 	pay_off = (size_t)offset & ~PAGE_MASK;
 	buff_off = (size_t)buf & ~PAGE_MASK;
 
 	if (!is_dma_copy_aligned(device, pay_off, buff_off, len))
 		goto err;
 
-	unmap = dmaengine_get_unmap_data(device->dev, 2, GFP_NOWAIT);
+	unmap = dmaengine_get_unmap_data(dma_dev, 2, GFP_NOWAIT);
 	if (!unmap)
 		goto err;
 
 	unmap->len = len;
-	unmap->addr[0] = dma_map_phys(device->dev, virt_to_phys(offset),
+	unmap->addr[0] = dma_map_phys(dma_dev, virt_to_phys(offset),
 				      len, DMA_TO_DEVICE, 0);
-	if (dma_mapping_error(device->dev, unmap->addr[0]))
+	if (dma_mapping_error(dma_dev, unmap->addr[0]))
 		goto err_get_unmap;
 
 	unmap->to_cnt = 1;
 
-	unmap->addr[1] = dma_map_phys(device->dev, virt_to_phys(buf),
+	unmap->addr[1] = dma_map_phys(dma_dev, virt_to_phys(buf),
 				      len, DMA_FROM_DEVICE, 0);
-	if (dma_mapping_error(device->dev, unmap->addr[1]))
+	if (dma_mapping_error(dma_dev, unmap->addr[1]))
 		goto err_get_unmap;
 
 	unmap->from_cnt = 1;
@@ -1856,6 +1858,7 @@ static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
 {
 	struct dma_async_tx_descriptor *txd;
 	struct dma_chan *chan = qp->tx_dma_chan;
+	struct device *dma_dev = dmaengine_get_dma_device(chan);
 	struct dma_device *device;
 	size_t len = entry->len;
 	void *buf = entry->buf;
@@ -1872,14 +1875,14 @@ static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
 	if (!is_dma_copy_aligned(device, buff_off, dest_off, len))
 		goto err;
 
-	unmap = dmaengine_get_unmap_data(device->dev, 1, GFP_NOWAIT);
+	unmap = dmaengine_get_unmap_data(dma_dev, 1, GFP_NOWAIT);
 	if (!unmap)
 		goto err;
 
 	unmap->len = len;
-	unmap->addr[0] = dma_map_phys(device->dev, virt_to_phys(buf),
+	unmap->addr[0] = dma_map_phys(dma_dev, virt_to_phys(buf),
 				      len, DMA_TO_DEVICE, 0);
-	if (dma_mapping_error(device->dev, unmap->addr[0]))
+	if (dma_mapping_error(dma_dev, unmap->addr[0]))
 		goto err_get_unmap;
 
 	unmap->to_cnt = 1;
@@ -2026,6 +2029,7 @@ ntb_transport_create_queue(void *data, struct device *client_dev,
 	struct ntb_transport_qp *qp;
 	u64 qp_bit;
 	unsigned int free_queue;
+	struct device *tx_dev;
 	dma_cap_mask_t dma_mask;
 	int node;
 	int i;
@@ -2089,11 +2093,12 @@ ntb_transport_create_queue(void *data, struct device *client_dev,
 
 	qp->tx_mw_dma_addr = 0;
 	if (qp->tx_dma_chan) {
+		tx_dev = dmaengine_get_dma_device(qp->tx_dma_chan);
 		qp->tx_mw_dma_addr =
-			dma_map_resource(qp->tx_dma_chan->device->dev,
+			dma_map_resource(tx_dev,
 					 qp->tx_mw_phys, qp->tx_mw_size,
 					 DMA_FROM_DEVICE, 0);
-		if (dma_mapping_error(qp->tx_dma_chan->device->dev,
+		if (dma_mapping_error(tx_dev,
 				      qp->tx_mw_dma_addr)) {
 			qp->tx_mw_dma_addr = 0;
 			goto err1;
@@ -2142,7 +2147,7 @@ ntb_transport_create_queue(void *data, struct device *client_dev,
 	while ((entry = ntb_list_rm(&qp->ntb_rx_q_lock, &qp->rx_free_q)))
 		kfree(entry);
 	if (qp->tx_mw_dma_addr)
-		dma_unmap_resource(qp->tx_dma_chan->device->dev,
+		dma_unmap_resource(tx_dev,
 				   qp->tx_mw_dma_addr, qp->tx_mw_size,
 				   DMA_FROM_DEVICE, 0);
 	if (qp->tx_dma_chan)
@@ -2192,7 +2197,7 @@ void ntb_transport_free_queue(struct ntb_transport_qp *qp)
 		dma_sync_wait(chan, qp->last_cookie);
 		dmaengine_terminate_all(chan);
 
-		dma_unmap_resource(chan->device->dev,
+		dma_unmap_resource(dmaengine_get_dma_device(chan),
 				   qp->tx_mw_dma_addr, qp->tx_mw_size,
 				   DMA_FROM_DEVICE, 0);
 
diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index dfd175f79e8f0..b936f15079df2 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -799,7 +799,7 @@ static int perf_copy_chunk(struct perf_thread *pthr,
 		goto ret_check_tsync;
 	}
 
-	dma_dev = pthr->dma_chan->device->dev;
+	dma_dev = dmaengine_get_dma_device(pthr->dma_chan);
 
 	if (!is_dma_copy_aligned(pthr->dma_chan->device, offset_in_page(src),
 				 offset_in_page(dst), len))
@@ -869,6 +869,7 @@ static bool perf_dma_filter(struct dma_chan *chan, void *data)
 static int perf_init_test(struct perf_thread *pthr)
 {
 	struct perf_ctx *perf = pthr->perf;
+	struct device *dma_dev;
 	dma_cap_mask_t dma_mask;
 	struct perf_peer *peer = pthr->perf->test_peer;
 
@@ -890,19 +891,20 @@ static int perf_init_test(struct perf_thread *pthr)
 			pthr->tidx);
 		goto err_free;
 	}
+	dma_dev = dmaengine_get_dma_device(pthr->dma_chan);
 	peer->dma_dst_addr =
-		dma_map_resource(pthr->dma_chan->device->dev,
+		dma_map_resource(dma_dev,
 				 peer->out_phys_addr, peer->outbuf_size,
 				 DMA_FROM_DEVICE, 0);
-	if (dma_mapping_error(pthr->dma_chan->device->dev,
+	if (dma_mapping_error(dma_dev,
 			      peer->dma_dst_addr)) {
-		dev_err(pthr->dma_chan->device->dev, "%d: Failed to map DMA addr\n",
+		dev_err(dma_dev, "%d: Failed to map DMA addr\n",
 			pthr->tidx);
 		peer->dma_dst_addr = 0;
 		dma_release_channel(pthr->dma_chan);
 		goto err_free;
 	}
-	dev_dbg(pthr->dma_chan->device->dev, "%d: Map MMIO %pa to DMA addr %pad\n",
+	dev_dbg(dma_dev, "%d: Map MMIO %pa to DMA addr %pad\n",
 			pthr->tidx,
 			&peer->out_phys_addr,
 			&peer->dma_dst_addr);
@@ -1003,7 +1005,7 @@ static void perf_clear_test(struct perf_thread *pthr)
 	 */
 	(void)dmaengine_terminate_sync(pthr->dma_chan);
 	if (pthr->perf->test_peer->dma_dst_addr)
-		dma_unmap_resource(pthr->dma_chan->device->dev,
+		dma_unmap_resource(dmaengine_get_dma_device(pthr->dma_chan),
 				   pthr->perf->test_peer->dma_dst_addr,
 				   pthr->perf->test_peer->outbuf_size,
 				   DMA_FROM_DEVICE, 0);
-- 
2.43.0


^ permalink raw reply	[flat|nested] 2+ messages in thread
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2026-09-21 20:39 [PATCH v2 1/1] ntb: use dmaengine_get_dma_device() instead of chan->device->dev Frank.Li
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