[PATCH v3 4/5] ntb: add DMA error handling for TX DMA

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Adding support on the tx DMA path to allow recovery of errors when DMA
responds with error status and abort all the subsequent ops.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 0 files changed

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 2ef9d913..bdb2001 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -102,6 +102,10 @@ struct ntb_queue_entry {
 	void *buf;
 	unsigned int len;
 	unsigned int flags;
+	struct dma_async_tx_descriptor *txd;
+	int retries;
+	int errors;
+	unsigned int tx_index;
 
 	struct ntb_transport_qp *qp;
 	union {
@@ -258,6 +262,9 @@ enum {
 static void ntb_transport_rxc_db(unsigned long data);
 static const struct ntb_ctx_ops ntb_transport_ops;
 static struct ntb_client ntb_transport_client;
+static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
+			       struct ntb_queue_entry *entry);
+static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset);
 
 static int ntb_transport_bus_match(struct device *dev,
 				   struct device_driver *drv)
@@ -1444,6 +1451,33 @@ static void ntb_tx_copy_callback(void *data)
 	struct ntb_queue_entry *entry = data;
 	struct ntb_transport_qp *qp = entry->qp;
 	struct ntb_payload_header __iomem *hdr = entry->tx_hdr;
+	struct dma_async_tx_descriptor *txd;
+
+	txd = entry->txd;
+
+	/* we need to check DMA results if we are using DMA */
+	if (txd) {
+		switch (txd->result) {
+		case ERR_DMA_READ:
+		case ERR_DMA_WRITE:
+			entry->errors++;
+		case ERR_DMA_ABORT:
+		{
+			void __iomem *offset =
+				qp->tx_mw + qp->tx_max_frame *
+				entry->tx_index;
+
+			/* resubmit via CPU */
+			ntb_memcpy_tx(entry, offset);
+			qp->tx_memcpy++;
+			return;
+		}
+
+		case ERR_DMA_NONE:
+		default:
+			break;
+		}
+	}
 
 	iowrite32(entry->flags | DESC_DONE_FLAG, &hdr->flags);
 
@@ -1482,37 +1516,21 @@ static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset)
 	ntb_tx_copy_callback(entry);
 }
 
-static void ntb_async_tx(struct ntb_transport_qp *qp,
-			 struct ntb_queue_entry *entry)
+static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
+			       struct ntb_queue_entry *entry)
 {
-	struct ntb_payload_header __iomem *hdr;
-	struct dma_async_tx_descriptor *txd;
 	struct dma_chan *chan = qp->tx_dma_chan;
 	struct dma_device *device;
+	size_t len = entry->len;
+	void *buf = entry->buf;
 	size_t dest_off, buff_off;
 	struct dmaengine_unmap_data *unmap;
 	dma_addr_t dest;
 	dma_cookie_t cookie;
-	void __iomem *offset;
-	size_t len = entry->len;
-	void *buf = entry->buf;
 	int retries = 0;
 
-	offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
-	hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
-	entry->tx_hdr = hdr;
-
-	iowrite32(entry->len, &hdr->len);
-	iowrite32((u32)qp->tx_pkts, &hdr->ver);
-
-	if (!chan)
-		goto err;
-
-	if (len < copy_bytes)
-		goto err;
-
 	device = chan->device;
-	dest = qp->tx_mw_phys + qp->tx_max_frame * qp->tx_index;
+	dest = qp->tx_mw_phys + qp->tx_max_frame * entry->tx_index;
 	buff_off = (size_t)buf & ~PAGE_MASK;
 	dest_off = (size_t)dest & ~PAGE_MASK;
 
@@ -1532,39 +1550,74 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
 	unmap->to_cnt = 1;
 
 	for (retries = 0; retries < DMA_RETRIES; retries++) {
-		txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0],
-						     len, DMA_PREP_INTERRUPT);
-		if (txd)
+		entry->txd = device->device_prep_dma_memcpy(chan, dest,
+							    unmap->addr[0], len,
+							    DMA_PREP_INTERRUPT);
+		if (entry->txd)
 			break;
 
 		set_current_state(TASK_INTERRUPTIBLE);
 		schedule_timeout(DMA_OUT_RESOURCE_TO);
 	}
 
-	if (!txd) {
+	if (!entry->txd) {
 		qp->dma_tx_prep_err++;
 		goto err_get_unmap;
 	}
 
-	txd->callback = ntb_tx_copy_callback;
-	txd->callback_param = entry;
-	dma_set_unmap(txd, unmap);
+	entry->txd->callback = ntb_tx_copy_callback;
+	entry->txd->callback_param = entry;
+	dma_set_unmap(entry->txd, unmap);
 
-	cookie = dmaengine_submit(txd);
+	cookie = dmaengine_submit(entry->txd);
 	if (dma_submit_error(cookie))
 		goto err_set_unmap;
 
 	dmaengine_unmap_put(unmap);
 
 	dma_async_issue_pending(chan);
-	qp->tx_async++;
 
-	return;
+	return 0;
 err_set_unmap:
 	dmaengine_unmap_put(unmap);
 err_get_unmap:
 	dmaengine_unmap_put(unmap);
 err:
+	return -ENXIO;
+}
+
+static void ntb_async_tx(struct ntb_transport_qp *qp,
+			 struct ntb_queue_entry *entry)
+{
+	struct ntb_payload_header __iomem *hdr;
+	struct dma_chan *chan = qp->tx_dma_chan;
+	void __iomem *offset;
+	int res;
+
+	entry->tx_index = qp->tx_index;
+	offset = qp->tx_mw + qp->tx_max_frame * entry->tx_index;
+	hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
+	entry->tx_hdr = hdr;
+
+	iowrite32(entry->len, &hdr->len);
+	iowrite32((u32)qp->tx_pkts, &hdr->ver);
+
+	if (!chan)
+		goto err;
+
+	if (entry->len < copy_bytes)
+		goto err;
+
+	res = ntb_async_tx_submit(qp, entry);
+	if (res < 0)
+		goto err;
+
+	if (!entry->retries)
+		qp->tx_async++;
+
+	return;
+
+err:
 	ntb_memcpy_tx(entry, offset);
 	qp->tx_memcpy++;
 }
@@ -1940,6 +1993,10 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
 	entry->buf = data;
 	entry->len = len;
 	entry->flags = 0;
+	entry->errors = 0;
+	entry->retries = 0;
+	entry->tx_index = 0;
+	entry->txd = NULL;
 
 	rc = ntb_process_tx(qp, entry);
 	if (rc)

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