[PATCH net-next] eth: bnxt: add netmem TX support

Taehee Yoo
2025-06-17T09:45:53Z

Use netmem_dma_*() helpers and declare netmem_tx to support netmem TX.
By this change, all bnxt devices will support the netmem TX.

bnxt_start_xmit() uses memcpy() if a packet is too small. However,
netmem packets are unreadable, so memcpy() is not allowed.
It should check whether an skb is readable, and if an SKB is unreadable,
it is processed by the normal transmission logic.

netmem TX can be tested with ncdevmem.c

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 28 ++++++++++++++---------
1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 869580b6f70d..4de9dc123a18 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -477,6 +477,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
struct bnxt_tx_ring_info *txr;
struct bnxt_sw_tx_bd *tx_buf;
__le32 lflags = 0;
+ skb_frag_t *frag;

i = skb_get_queue_mapping(skb);
if (unlikely(i >= bp->tx_nr_rings)) {
@@ -563,7 +564,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
lflags |= cpu_to_le32(TX_BD_FLAGS_NO_CRC);

if (free_size == bp->tx_ring_size && length <= bp->tx_push_thresh &&
- !lflags) {
+ skb_frags_readable(skb) && !lflags) {
struct tx_push_buffer *tx_push_buf = txr->tx_push;
struct tx_push_bd *tx_push = &tx_push_buf->push_bd;
struct tx_bd_ext *tx_push1 = &tx_push->txbd2;
@@ -598,9 +599,9 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
skb_copy_from_linear_data(skb, pdata, len);
pdata += len;
for (j = 0; j < last_frag; j++) {
- skb_frag_t *frag = &skb_shinfo(skb)->frags[j];
void *fptr;

+ frag = &skb_shinfo(skb)->frags[j];
fptr = skb_frag_address_safe(frag);
if (!fptr)
goto normal_tx;
@@ -708,8 +709,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
cpu_to_le32(cfa_action << TX_BD_CFA_ACTION_SHIFT);
txbd0 = txbd;
for (i = 0; i < last_frag; i++) {
- skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
-
+ frag = &skb_shinfo(skb)->frags[i];
prod = NEXT_TX(prod);
txbd = &txr->tx_desc_ring[TX_RING(bp, prod)][TX_IDX(prod)];

@@ -721,7 +721,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
goto tx_dma_error;

tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)];
- dma_unmap_addr_set(tx_buf, mapping, mapping);
+ netmem_dma_unmap_addr_set(skb_frag_netmem(frag), tx_buf,
+ mapping, mapping);

txbd->tx_bd_haddr = cpu_to_le64(mapping);

@@ -778,9 +779,11 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
for (i = 0; i < last_frag; i++) {
prod = NEXT_TX(prod);
tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)];
- dma_unmap_page(&pdev->dev, dma_unmap_addr(tx_buf, mapping),
- skb_frag_size(&skb_shinfo(skb)->frags[i]),
- DMA_TO_DEVICE);
+ frag = &skb_shinfo(skb)->frags[i];
+ netmem_dma_unmap_page_attrs(&pdev->dev,
+ dma_unmap_addr(tx_buf, mapping),
+ skb_frag_size(frag),
+ DMA_TO_DEVICE, 0);
}

tx_free:
@@ -3422,9 +3425,11 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
skb_frag_t *frag = &skb_shinfo(skb)->frags[j];

tx_buf = &txr->tx_buf_ring[ring_idx];
- dma_unmap_page(&pdev->dev,
- dma_unmap_addr(tx_buf, mapping),
- skb_frag_size(frag), DMA_TO_DEVICE);
+ netmem_dma_unmap_page_attrs(&pdev->dev,
+ dma_unmap_addr(tx_buf,
+ mapping),
+ skb_frag_size(frag),
+ DMA_TO_DEVICE, 0);
}
dev_kfree_skb(skb);
}
@@ -16713,6 +16718,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
if (BNXT_SUPPORTS_QUEUE_API(bp))
dev->queue_mgmt_ops = &bnxt_queue_mgmt_ops;
dev->request_ops_lock = true;
+ dev->netmem_tx = true;

rc = register_netdev(dev);
if (rc)
--
2.34.1