[PATCH net-next v6 06/14] net: lan966x: use a dedicated device for DMA operations
From: Daniel Machon <daniel.machon@microchip.com>
Date: 2026-09-09 13:00:48
Also in:
bpf, linux-arm-kernel, lkml
Subsystem:
microchip lan966x ethernet driver, networking drivers, the rest · Maintainers:
Horatiu Vultur, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
In preparation for the PCIe FDMA implementation, add lan966x->dma_dev, resolved once at probe time, and use it for every DMA operation the FDMA path performs: coherent allocations, streaming mappings and the RX page pool. Natively, dma_dev is lan966x->dev, so there is no functional change. Since dma_dev differs from dev only on the PCIe path, add lan966x_is_pci() on top of it, for the later PCIe patches to key off. Signed-off-by: Daniel Machon <daniel.machon@microchip.com> --- .../net/ethernet/microchip/lan966x/lan966x_fdma.c | 30 +++++++++++----------- .../net/ethernet/microchip/lan966x/lan966x_main.c | 16 ++++++++++++ .../net/ethernet/microchip/lan966x/lan966x_main.h | 10 ++++++++ 3 files changed, 41 insertions(+), 15 deletions(-)
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
index 1311b79bd11f..15fc59cb4ad7 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c@@ -80,7 +80,7 @@ static int lan966x_fdma_rx_alloc_page_pool(struct lan966x_rx *rx) .flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV, .pool_size = rx->fdma.n_dcbs, .nid = NUMA_NO_NODE, - .dev = lan966x->dev, + .dev = lan966x->dma_dev, .dma_dir = DMA_FROM_DEVICE, .offset = XDP_PACKET_HEADROOM, .max_len = rx->max_mtu -
@@ -126,7 +126,7 @@ static int lan966x_fdma_rx_alloc(struct lan966x_rx *rx) if (err) return err; - err = fdma_alloc_coherent(lan966x->dev, fdma); + err = fdma_alloc_coherent(lan966x->dma_dev, fdma); if (err) { page_pool_destroy(rx->page_pool); return err;
@@ -210,7 +210,7 @@ static int lan966x_fdma_tx_alloc(struct lan966x_tx *tx) if (!tx->dcbs_buf) return -ENOMEM; - err = fdma_alloc_coherent(lan966x->dev, fdma); + err = fdma_alloc_coherent(lan966x->dma_dev, fdma); if (err) goto out;
@@ -230,7 +230,7 @@ static void lan966x_fdma_tx_free(struct lan966x_tx *tx) struct lan966x *lan966x = tx->lan966x; kfree(tx->dcbs_buf); - fdma_free_coherent(lan966x->dev, &tx->fdma); + fdma_free_coherent(lan966x->dma_dev, &tx->fdma); } static void lan966x_fdma_tx_activate(struct lan966x_tx *tx)
@@ -355,7 +355,7 @@ static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight) dcb_buf->used = false; if (dcb_buf->use_skb) { - dma_unmap_single(lan966x->dev, + dma_unmap_single(lan966x->dma_dev, dcb_buf->dma_addr, dcb_buf->len, DMA_TO_DEVICE);
@@ -364,7 +364,7 @@ static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight) napi_consume_skb(dcb_buf->data.skb, weight); } else { if (dcb_buf->xdp_ndo) - dma_unmap_single(lan966x->dev, + dma_unmap_single(lan966x->dma_dev, dcb_buf->dma_addr, dcb_buf->len, DMA_TO_DEVICE);
@@ -400,7 +400,7 @@ static int lan966x_fdma_rx_check_frame(struct lan966x_rx *rx, u64 *src_port) if (unlikely(!page)) return FDMA_ERROR; - dma_sync_single_for_cpu(lan966x->dev, + dma_sync_single_for_cpu(lan966x->dma_dev, (dma_addr_t)db->dataptr + XDP_PACKET_HEADROOM, FDMA_DCB_STATUS_BLOCKL(db->status), DMA_FROM_DEVICE);
@@ -635,11 +635,11 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len) lan966x_ifh_set_bypass(ifh, 1); lan966x_ifh_set_port(ifh, BIT_ULL(port->chip_port)); - dma_addr = dma_map_single(lan966x->dev, + dma_addr = dma_map_single(lan966x->dma_dev, xdpf->data - IFH_LEN_BYTES, xdpf->len + IFH_LEN_BYTES, DMA_TO_DEVICE); - if (dma_mapping_error(lan966x->dev, dma_addr)) { + if (dma_mapping_error(lan966x->dma_dev, dma_addr)) { ret = NETDEV_TX_OK; goto out; }
@@ -655,7 +655,7 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len) lan966x_ifh_set_port(ifh, BIT_ULL(port->chip_port)); dma_addr = page_pool_get_dma_addr(page); - dma_sync_single_for_device(lan966x->dev, + dma_sync_single_for_device(lan966x->dma_dev, dma_addr + XDP_PACKET_HEADROOM, len + IFH_LEN_BYTES, DMA_TO_DEVICE);
@@ -734,9 +734,9 @@ int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev) memcpy(skb->data, ifh, IFH_LEN_BYTES); skb_put(skb, 4); - dma_addr = dma_map_single(lan966x->dev, skb->data, skb->len, + dma_addr = dma_map_single(lan966x->dma_dev, skb->data, skb->len, DMA_TO_DEVICE); - if (dma_mapping_error(lan966x->dev, dma_addr)) { + if (dma_mapping_error(lan966x->dma_dev, dma_addr)) { dev->stats.tx_dropped++; err = NETDEV_TX_OK; goto release;
@@ -842,7 +842,7 @@ static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu) page_pool_put_full_page(page_pool, old_pages[i][j], false); - fdma_free_coherent(lan966x->dev, &fdma_rx_old); + fdma_free_coherent(lan966x->dma_dev, &fdma_rx_old); page_pool_destroy(page_pool);
@@ -992,7 +992,7 @@ int lan966x_fdma_init(struct lan966x *lan966x) err = lan966x_fdma_tx_alloc(&lan966x->tx); if (err) { - fdma_free_coherent(lan966x->dev, &lan966x->rx.fdma); + fdma_free_coherent(lan966x->dma_dev, &lan966x->rx.fdma); page_pool_destroy(lan966x->rx.page_pool); return err; }
@@ -1014,7 +1014,7 @@ void lan966x_fdma_deinit(struct lan966x *lan966x) napi_disable(&lan966x->napi); lan966x_fdma_rx_free_pages(&lan966x->rx); - fdma_free_coherent(lan966x->dev, &lan966x->rx.fdma); + fdma_free_coherent(lan966x->dma_dev, &lan966x->rx.fdma); page_pool_destroy(lan966x->rx.page_pool); lan966x_fdma_tx_free(&lan966x->tx); }
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index 1179a6e127c5..2741f7c9fa4c 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c@@ -7,6 +7,7 @@ #include <linux/ip.h> #include <linux/of.h> #include <linux/of_net.h> +#include <linux/pci.h> #include <linux/phy/phy.h> #include <linux/platform_device.h> #include <linux/reset.h>
@@ -1081,6 +1082,20 @@ static int lan966x_reset_switch(struct lan966x *lan966x) return 0; } +/* When enumerated over PCIe, dev is a platform device with no + * iommus/dma-ranges of its own, so DMA must target the PCIe endpoint instead. + * The result differs from dev only in that case; lan966x_is_pci() relies on it. + */ +static struct device *lan966x_get_dma_dev(struct device *dev) +{ + for (struct device *p = dev->parent; p; p = p->parent) { + if (dev_is_pci(p)) + return p; + } + + return dev; +} + static int lan966x_probe(struct platform_device *pdev) { struct fwnode_handle *ports, *portnp;
@@ -1094,6 +1109,7 @@ static int lan966x_probe(struct platform_device *pdev) platform_set_drvdata(pdev, lan966x); lan966x->dev = &pdev->dev; + lan966x->dma_dev = lan966x_get_dma_dev(lan966x->dev); if (!device_get_mac_address(&pdev->dev, mac_addr)) { ether_addr_copy(lan966x->base_mac, mac_addr);
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
index 83c361abb789..3f09f8ddf620 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h@@ -270,6 +270,9 @@ struct lan966x_skb_cb { struct lan966x { struct device *dev; + /* Device used for DMA; the PCIe endpoint when enumerated over PCIe. */ + struct device *dma_dev; + u8 num_phys_ports; struct lan966x_port **ports;
@@ -573,6 +576,13 @@ void lan966x_fdma_wakeup_netdev(struct lan966x *lan966x); int lan966x_fdma_get_max_frame(struct lan966x *lan966x); int lan966x_qsys_sw_status(struct lan966x *lan966x); +/* dma_dev differs from dev only on the PCIe path. */ +static inline bool lan966x_is_pci(struct lan966x *lan966x) +{ + return IS_ENABLED(CONFIG_MCHP_LAN966X_PCI) && + lan966x->dma_dev != lan966x->dev; +} + int lan966x_lag_port_join(struct lan966x_port *port, struct net_device *brport_dev, struct net_device *bond,
--
2.34.1