On Wed, 20 May 2026 10:12:21 +0200 Daniel Machon wrote:
> Add PCIe FDMA support for lan966x. The PCIe FDMA path uses contiguous
> DMA buffers mapped through the endpoint's ATU, with memcpy-based frame
> transfer instead of per-page DMA mappings.
>
> With PCIe FDMA, throughput increases from ~33 Mbps (register-based I/O)
> to ~620 Mbps on an Intel x86 host with a lan966x PCIe card.
> diff --git a/drivers/net/ethernet/microchip/lan966x/Makefile b/drivers/net/ethernet/microchip/lan966x/Makefile
> index 4cdbe263502c..ac0beceb2a0d 100644
> --- a/drivers/net/ethernet/microchip/lan966x/Makefile
> +++ b/drivers/net/ethernet/microchip/lan966x/Makefile
> @@ -18,6 +18,10 @@ lan966x-switch-objs := lan966x_main.o lan966x_phylink.o lan966x_port.o \
> lan966x-switch-$(CONFIG_LAN966X_DCB) += lan966x_dcb.o
> lan966x-switch-$(CONFIG_DEBUG_FS) += lan966x_vcap_debugfs.o
>
> +ifdef CONFIG_MCHP_LAN966X_PCI
ifeq ()
would be more common in a Makefile?
> +lan966x-switch-y += lan966x_fdma_pci.o
> +endif
> +
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
> index cc3c7b6c65ae..7036b1d937d5 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>
> @@ -49,6 +50,9 @@ struct lan966x_main_io_resource {
> static const struct lan966x_main_io_resource lan966x_main_iomap[] = {
> { TARGET_CPU, 0xc0000, 0 }, /* 0xe00c0000 */
> { TARGET_FDMA, 0xc0400, 0 }, /* 0xe00c0400 */
> +#if IS_ENABLED(CONFIG_MCHP_LAN966X_PCI)
why config option being enabled changes the targets?
Can someone with a non-PCI device enable that option too
(sure it would be useless but given that/if they can guarding
with an #if seems like a waste of LoC)
> + { TARGET_PCIE_DBI, 0x400000, 0 }, /* 0xe0400000 */
> +#endif
> { TARGET_ORG, 0, 1 }, /* 0xe2000000 */
> { TARGET_GCB, 0x4000, 1 }, /* 0xe2004000 */
> { TARGET_QS, 0x8000, 1 }, /* 0xe2008000 */
> @@ -1100,6 +1104,13 @@ static int lan966x_reset_switch(struct lan966x *lan966x)
>
> static const struct lan966x_fdma_ops *lan966x_get_fdma_ops(struct device *dev)
> {
> +#if IS_ENABLED(CONFIG_MCHP_LAN966X_PCI)
> + for (struct device *p = dev->parent; p; p = p->parent) {
> + if (dev_is_pci(p))
If the PCIe devices also use an intermediate platform device for
probing, can't they explicitly have some flag / state to indicate
they are PCIe? The device walk in such a constrained env seems
like an overkill
> + return &lan966x_fdma_pci_ops;
> + }
> +#endif
> +
> return &lan966x_fdma_ops;
> }
>
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> index 5f4dbeda17cd..e7fdd4447fb6 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> @@ -17,6 +17,9 @@
> #include <net/xdp.h>
>
> #include <fdma_api.h>
> +#if IS_ENABLED(CONFIG_MCHP_LAN966X_PCI)
> +#include <fdma_pci.h>
> +#endif
Conditional #includes make build testing harder, better to avoid them
> #include <vcap_api.h>
> #include <vcap_api_client.h>
>
> @@ -288,6 +291,10 @@ struct lan966x {
>
> void __iomem *regs[NUM_TARGETS];
>
> +#if IS_ENABLED(CONFIG_MCHP_LAN966X_PCI)
> + struct fdma_pci_atu atu;
> +#endif
> +
> int shared_queue_sz;
>
> u8 base_mac[ETH_ALEN];
> @@ -586,6 +593,10 @@ 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);
>
> +#if IS_ENABLED(CONFIG_MCHP_LAN966X_PCI)
> +extern const struct lan966x_fdma_ops lan966x_fdma_pci_ops;
> +#endif
There should be no need to wrap extern in an #if