microchipsw: add MTU change support

Add the MTU change support ported from Microchip BSP kernel. It will be sent upstream as well. Signed-off-by: Robert Marko <robert.marko@sartura.hr>
2026-05-05 09:56:12 +02:00 · 2026-03-24 18:42:52 +01:00 · 2026-03-24 18:42:52 +01:00 · 0a82d6054c
commit 0a82d6054c
parent c5455f60ab
5 changed files with 567 additions and 0 deletions
--- a/target/linux/microchipsw/patches-6.12/126-net-lan969x-correct-RGMII-port-mapping-index.patch
+++ b/target/linux/microchipsw/patches-6.12/126-net-lan969x-correct-RGMII-port-mapping-index.patch
@ -0,0 +1,37 @@
+From 44ed546c4231fbf9d0c92738c2c48c49f8249f48 Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko@sartura.hr>
+Date: Tue, 24 Mar 2026 12:02:05 +0100
+Subject: [PATCH 126/130] net: lan969x: correct RGMII port mapping index
+
+Currently, the lan969x_port_dev_mapping does not check for RGMII ports
+and just returns the physical port index.
+
+However, this does not work for RGMII ports as they have dedicated DEVRGMII
+register space with an dedicated instance per RGMII port.
+
+So, check if requested port index is an RGMII port and return the correct
+DEVRGMII index.
+
+Signed-off-by: Robert Marko <robert.marko@sartura.hr>
+---
+ drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.c | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+--- a/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.c
+++ b/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.c
+@@ -142,6 +142,15 @@ static u32 lan969x_get_dev_mode_bit(stru
+ 
+ static u32 lan969x_port_dev_mapping(struct sparx5 *sparx5, int port)
+ {
+	if (lan969x_port_is_rgmii(port)) {
+		switch (port) {
+		case 28:
+			return 0;
+		case 29:
+			return 1;
+		}
+	}
+
+ 	if (lan969x_port_is_5g(port)) {
+ 		switch (port) {
+ 		case 9:
--- a/target/linux/microchipsw/patches-6.12/127-net-sparx5-add-MTU-change-framework.patch
+++ b/target/linux/microchipsw/patches-6.12/127-net-sparx5-add-MTU-change-framework.patch
@ -0,0 +1,264 @@
+From 372e0295a1dbf0ea4333183ac82b8620bef9c0dc Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko@sartura.hr>
+Date: Tue, 24 Mar 2026 12:19:03 +0100
+Subject: [PATCH 127/130] net: sparx5: add MTU change framework
+
+Port the MTU change framework from Microchip BSP kernel.
+This only wires the generic SparX-5 and LAN969x code.
+
+SparX-5 and LAN969x specific code to actually change the MTU will follow.
+
+Signed-off-by: Robert Marko <robert.marko@sartura.hr>
+---
+ .../net/ethernet/microchip/sparx5/Makefile    |   2 +-
+ .../ethernet/microchip/sparx5/sparx5_fdma.c   |  20 +++
+ .../ethernet/microchip/sparx5/sparx5_main.h   |   8 ++
+ .../microchip/sparx5/sparx5_main_regs.h       |  11 ++
+ .../ethernet/microchip/sparx5/sparx5_mtu.c    | 130 ++++++++++++++++++
+ 5 files changed, 170 insertions(+), 1 deletion(-)
+ create mode 100644 drivers/net/ethernet/microchip/sparx5/sparx5_mtu.c
+
+--- a/drivers/net/ethernet/microchip/sparx5/Makefile
+++ b/drivers/net/ethernet/microchip/sparx5/Makefile
+@@ -11,7 +11,7 @@ sparx5-switch-y  := sparx5_main.o sparx5
+  sparx5_ptp.o sparx5_pgid.o sparx5_tc.o sparx5_qos.o \
+  sparx5_vcap_impl.o sparx5_vcap_ag_api.o sparx5_tc_flower.o \
+  sparx5_tc_matchall.o sparx5_pool.o sparx5_sdlb.o sparx5_police.o \
+- sparx5_psfp.o sparx5_mirror.o sparx5_regs.o
+ sparx5_psfp.o sparx5_mirror.o sparx5_regs.o sparx5_mtu.o
+ 
+ sparx5-switch-$(CONFIG_SPARX5_DCB) += sparx5_dcb.o
+ sparx5-switch-$(CONFIG_DEBUG_FS) += sparx5_vcap_debugfs.o
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+@@ -462,6 +462,15 @@ int sparx5_fdma_start(struct sparx5 *spa
+ 	sparx5_fdma_rx_activate(sparx5, rx);
+ 	sparx5_fdma_tx_activate(sparx5, tx);
+ 
+	for (int i = 0; i < sparx5->data->consts->n_ports; i++) {
+		struct sparx5_port *port = sparx5->ports[i];
+
+		if (!port)
+			continue;
+		if (netif_queue_stopped(port->ndev))
+			netif_wake_queue(port->ndev);
+	}
+
+ 	return 0;
+ }
+ 
+@@ -471,6 +480,7 @@ int sparx5_fdma_stop(struct sparx5 *spar
+ 	struct sparx5_tx *tx = &sparx5->tx;
+ 	u32 val;
+ 
+	napi_synchronize(&sparx5->rx.napi);
+ 	napi_disable(&rx->napi);
+ 
+ 	/* Stop the fdma and channel interrupts */
+@@ -482,5 +492,15 @@ int sparx5_fdma_stop(struct sparx5 *spar
+ 			  FDMA_PORT_CTRL_XTR_BUF_IS_EMPTY_GET(val) == 0,
+ 			  500, 10000, 0, sparx5);
+ 
+	for (int i = 0; i < sparx5->data->consts->n_ports; i++) {
+		struct sparx5_port *port = sparx5->ports[i];
+
+		if (!port)
+			continue;
+		netif_stop_queue(port->ndev);
+	}
+
+	netif_napi_del(&sparx5->rx.napi);
+
+ 	return 0;
+ }
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
+@@ -102,6 +102,7 @@ enum sparx5_feature {
+ #define PGID_TABLE_SIZE	       3290
+ 
+ #define IFH_LEN                9 /* 36 bytes */
+#define IFH_LEN_BYTES          (IFH_LEN * sizeof(u32))
+ #define NULL_VID               0
+ #define SPX5_MACT_PULL_DELAY   (2 * HZ)
+ #define SPX5_STATS_CHECK_DELAY (1 * HZ)
+@@ -188,6 +189,7 @@ struct sparx5_tx {
+ 	struct sparx5_tx_buf *dbs;
+ 	u64 packets;
+ 	u64 dropped;
+	u16 max_mtu;
+ };
+ 
+ struct sparx5_port_config {
+@@ -348,6 +350,8 @@ struct sparx5_ops {
+ 	int (*fdma_poll)(struct napi_struct *napi, int weight);
+ 	int (*fdma_xmit)(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb,
+ 			 struct net_device *dev);
+	int (*fdma_resize)(struct sparx5 *sparx5);
+	u32 (*get_mtu)(struct sparx5 *sparx5);
+ };
+ 
+ struct sparx5_main_io_resource {
+@@ -712,6 +716,10 @@ void sparx5_mirror_del(struct sparx5_mal
+ void sparx5_mirror_stats(struct sparx5_mall_entry *entry,
+ 			 struct flow_stats *fstats);
+ 
+/* sparx5_mtu.c */
+int sparx5_mtu_change(struct net_device *dev, int new_mtu);
+u32 sparx5_mtu_max(struct sparx5 *sparx5);
+
+ /* Clock period in picoseconds */
+ static inline u32 sparx5_clk_period(enum sparx5_core_clockfreq cclock)
+ {
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main_regs.h
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main_regs.h
+@@ -8204,6 +8204,17 @@ extern const struct sparx5_regs *regs;
+ 	FIELD_GET(DEVRGMII_MAC_ENA_CFG_TX_ENA, x)
+ 
+ /* LAN969X ONLY */
+/* DEV1G:MAC_CFG_STATUS:MAC_MAXLEN_CFG */
+#define DEVRGMII_MAC_MAXLEN_CFG(t)                                             \
+	__REG(TARGET_DEVRGMII, t, 2, 36, 0, 1, 36, 8, 0, 1, 4)
+
+#define DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN          GENMASK(15, 0)
+#define DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN_SET(x)\
+	FIELD_PREP(DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN, x)
+#define DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN_GET(x)\
+	FIELD_GET(DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN, x)
+
+/* LAN969X ONLY */
+ /* DEV1G:MAC_CFG_STATUS:MAC_TAGS_CFG */
+ #define DEVRGMII_MAC_TAGS_CFG(t)                                               \
+ 	__REG(TARGET_DEVRGMII, t, 2, 36, 0, 1, 36, 12, 0, 1, 4)
+--- /dev/null
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_mtu.c
+@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Microchip Sparx5 Switch driver
+ *
+ * Copyright (c) 2024 Microchip Technology Inc. and its subsidiaries.
+ */
+
+#include "sparx5_main.h"
+
+#define SPX5_HW_MTU(mtu) ((mtu) + ETH_ALEN + IFH_LEN * 4 + ETH_FCS_LEN)
+
+/* Get the MTU for this port */
+static u32 sparx5_mtu_get(struct sparx5_port *port)
+{
+	struct sparx5 *sparx5 = port->sparx5;
+	const struct sparx5_ops *ops = sparx5->data->ops;
+	u32 val;
+
+	/* We always set 2G5 or RGMII MTU, so there is no point in trying to
+	 * read high-speed MAC MTU here
+	 */
+	if (ops->is_port_rgmii(port->portno)) {
+		u32 idx = ops->get_port_dev_index(sparx5, port->portno);
+		val = spx5_rd(sparx5, DEVRGMII_MAC_MAXLEN_CFG(idx));
+		return DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN_GET(val);
+	} else {
+		val = spx5_rd(sparx5, DEV2G5_MAC_MAXLEN_CFG(port->portno));
+		return DEV2G5_MAC_MAXLEN_CFG_MAX_LEN_GET(val);
+	}
+}
+
+/* Set the MTU for this port. */
+static void sparx5_mtu_set(struct sparx5_port *port, u32 new_mtu)
+{
+	struct sparx5 *sparx5 = port->sparx5;
+	const struct sparx5_ops *ops;
+	u32 idx, hw_mtu;
+
+	ops = sparx5->data->ops;
+	idx = ops->get_port_dev_index(sparx5, port->portno);
+	hw_mtu = SPX5_HW_MTU(new_mtu);
+
+	pr_debug("Setting MTU to: %u for portno (idx: %u): %u\n", new_mtu,
+		 port->portno, idx);
+
+	/* All port modules have a 2g5 shadow device (and DEV2G5 is indexed
+	 * by port number). Except the RGMII ports
+	 */
+	if (!ops->is_port_rgmii(port->portno))
+		spx5_rmw(DEV2G5_MAC_MAXLEN_CFG_MAX_LEN_SET(hw_mtu),
+			 DEV2G5_MAC_MAXLEN_CFG_MAX_LEN, sparx5,
+			 DEV2G5_MAC_MAXLEN_CFG(port->portno));
+
+	if (ops->is_port_rgmii(port->portno))
+		spx5_rmw(DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN_SET(hw_mtu),
+			DEVRGMII_MAC_MAXLEN_CFG_MAX_LEN, sparx5,
+			DEVRGMII_MAC_MAXLEN_CFG(idx));
+	else if (ops->is_port_2g5(port->portno))
+		return; /* Already configured. */
+	else if (ops->is_port_5g(port->portno))
+		spx5_rmw(DEV5G_MAC_MAXLEN_CFG_MAX_LEN_SET(hw_mtu),
+			 DEV5G_MAC_MAXLEN_CFG_MAX_LEN, sparx5,
+			 DEV5G_MAC_MAXLEN_CFG(idx));
+	else if (ops->is_port_10g(port->portno))
+		spx5_rmw(DEV10G_MAC_MAXLEN_CFG_MAX_LEN_SET(hw_mtu),
+			 DEV10G_MAC_MAXLEN_CFG_MAX_LEN, sparx5,
+			 DEV10G_MAC_MAXLEN_CFG(idx));
+	else
+		spx5_rmw(DEV25G_MAC_MAXLEN_CFG_MAX_LEN_SET(hw_mtu),
+			 DEV25G_MAC_MAXLEN_CFG_MAX_LEN, sparx5,
+			 DEV25G_MAC_MAXLEN_CFG(idx));
+}
+
+u32 sparx5_mtu_max(struct sparx5 *sparx5)
+{
+	u32 mtu_max = 0;
+
+	for (int i = 0; i < sparx5->data->consts->n_ports; i++) {
+		struct sparx5_port *port = sparx5->ports[i];
+		u32 mtu;
+
+		if (!port)
+			continue;
+
+		mtu = sparx5_mtu_get(port) + IFH_LEN_BYTES +
+		      SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) +
+		      VLAN_HLEN * 2 + XDP_PACKET_HEADROOM;
+
+		if (mtu > mtu_max)
+			mtu_max = mtu;
+	}
+
+	return mtu_max;
+}
+
+static int sparx5_mtu_fdma_set(struct sparx5 *sparx5)
+{
+	const struct sparx5_ops *ops = sparx5->data->ops;
+	u32 mtu_max = sparx5_mtu_max(sparx5);
+
+	/* We might not be using FDMA */
+	if (sparx5->fdma_irq <= 0)
+		return 0;
+
+	/* No need to restart FDMA if the MTU reflects the buffer size */
+	if (mtu_max == sparx5->tx.max_mtu)
+		return 0;
+
+	return ops->fdma_resize(sparx5);
+}
+
+int sparx5_mtu_change(struct net_device *dev, int new_mtu)
+{
+	struct sparx5_port *port = netdev_priv(dev);
+	struct sparx5 *sparx5 = port->sparx5;
+	int err, orig_mtu = dev->mtu;
+
+	/* Write MTU to hardware */
+	sparx5_mtu_set(port, new_mtu);
+
+	err = sparx5_mtu_fdma_set(sparx5);
+	if (err) {
+		sparx5_mtu_set(port, orig_mtu);
+		return err;
+	}
+
+	/* Let the stack know */
+	WRITE_ONCE(dev->mtu, new_mtu);
+
+	return 0;
+}
--- a/target/linux/microchipsw/patches-6.12/128-net-sparx5-add-MTU-change.patch
+++ b/target/linux/microchipsw/patches-6.12/128-net-sparx5-add-MTU-change.patch
@ -0,0 +1,107 @@
+From 466d22c9d3bdb2feda284c582d4f183879fc57ad Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko@sartura.hr>
+Date: Tue, 24 Mar 2026 12:26:51 +0100
+Subject: [PATCH 128/130] net: sparx5: add MTU change
+
+Add the required SparX-5 specific code to change the MTU.
+
+Signed-off-by: Robert Marko <robert.marko@sartura.hr>
+---
+ .../ethernet/microchip/sparx5/sparx5_fdma.c   | 52 +++++++++++++++++++
+ .../ethernet/microchip/sparx5/sparx5_main.c   |  2 +
+ .../ethernet/microchip/sparx5/sparx5_main.h   |  1 +
+ 3 files changed, 55 insertions(+)
+
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_fdma.c
+@@ -278,6 +278,8 @@ static void sparx5_fdma_rx_init(struct s
+ 	struct fdma *fdma = &rx->fdma;
+ 	int idx;
+ 
+	sparx5->rx.page_order =
+		round_up(sparx5->tx.max_mtu, PAGE_SIZE) / PAGE_SIZE - 1;
+ 	fdma->channel_id = channel;
+ 	fdma->n_dcbs = FDMA_DCB_MAX;
+ 	fdma->n_dbs = FDMA_RX_DCB_MAX_DBS;
+@@ -403,6 +405,8 @@ int sparx5_fdma_init(struct sparx5 *spar
+ {
+ 	int err;
+ 
+	sparx5->tx.max_mtu = sparx5->data->ops->get_mtu(sparx5);
+
+ 	/* Reset FDMA state */
+ 	spx5_wr(FDMA_CTRL_NRESET_SET(0), sparx5, FDMA_CTRL);
+ 	spx5_wr(FDMA_CTRL_NRESET_SET(1), sparx5, FDMA_CTRL);
+@@ -504,3 +508,51 @@ int sparx5_fdma_stop(struct sparx5 *spar
+ 
+ 	return 0;
+ }
+
+int sparx5_fdma_resize(struct sparx5 *sparx5)
+{
+	u32 old_mtu = sparx5->tx.max_mtu;
+	struct fdma tx_fdma_old = {0};
+	struct fdma rx_fdma_old = {0};
+	int err;
+
+	memcpy(&tx_fdma_old, &sparx5->tx.fdma, sizeof(struct fdma));
+	memcpy(&rx_fdma_old, &sparx5->rx.fdma, sizeof(struct fdma));
+
+	sparx5_fdma_stop(sparx5);
+
+	err = sparx5_fdma_init(sparx5);
+	if (err)
+		goto restore;
+
+	fdma_free_phys(&rx_fdma_old);
+	fdma_free_phys(&tx_fdma_old);
+
+	goto start;
+
+restore:
+
+	/* At this point, the FDMA engine is stopped and the stack is not
+	 * calling us for xmit. Restore the old MTU and rx,tx buffers and
+	 * restart the engine.
+	 */
+
+	sparx5->tx.max_mtu = old_mtu;
+	memcpy(&sparx5->tx.fdma, &tx_fdma_old, sizeof(struct fdma));
+	memcpy(&sparx5->rx.fdma, &rx_fdma_old, sizeof(struct fdma));
+
+	/* Old buffers have to be re-initialized. */
+
+	fdma_dcbs_init(&sparx5->rx.fdma,
+		       FDMA_DCB_INFO_DATAL(sparx5->rx.fdma.db_size),
+		       FDMA_DCB_STATUS_INTR);
+
+	fdma_dcbs_init(&sparx5->tx.fdma,
+		       FDMA_DCB_INFO_DATAL(sparx5->tx.fdma.db_size),
+		       FDMA_DCB_STATUS_DONE);
+
+start:
+	sparx5_fdma_start(sparx5);
+
+	return err;
+}
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
+@@ -1108,6 +1108,8 @@ static const struct sparx5_ops sparx5_op
+ 	.fdma_deinit             = &sparx5_fdma_deinit,
+ 	.fdma_poll               = &sparx5_fdma_napi_callback,
+ 	.fdma_xmit               = &sparx5_fdma_xmit,
+	.fdma_resize             = &sparx5_fdma_resize,
+	.get_mtu                 = &sparx5_mtu_max,
+ };
+ 
+ static const struct sparx5_match_data sparx5_desc = {
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.h
+@@ -472,6 +472,7 @@ int sparx5_fdma_xmit(struct sparx5 *spar
+ irqreturn_t sparx5_fdma_handler(int irq, void *args);
+ void sparx5_fdma_reload(struct sparx5 *sparx5, struct fdma *fdma);
+ void sparx5_fdma_injection_mode(struct sparx5 *sparx5);
+int sparx5_fdma_resize(struct sparx5 *sparx5);
+ 
+ /* sparx5_mactable.c */
+ void sparx5_mact_pull_work(struct work_struct *work);
--- a/target/linux/microchipsw/patches-6.12/129-net-lan969x-add-MTU-change.patch
+++ b/target/linux/microchipsw/patches-6.12/129-net-lan969x-add-MTU-change.patch
@ -0,0 +1,126 @@
+From b73c8d9fe87d3e35dc09faca85d5a5f9ee8e3f6c Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko@sartura.hr>
+Date: Tue, 24 Mar 2026 12:30:45 +0100
+Subject: [PATCH 129/130] net: lan969x: add MTU change
+
+Add the LAN969x specific code for MTU change.
+
+Signed-off-by: Robert Marko <robert.marko@sartura.hr>
+---
+ .../microchip/sparx5/lan969x/lan969x.c        |  2 +
+ .../microchip/sparx5/lan969x/lan969x.h        |  1 +
+ .../microchip/sparx5/lan969x/lan969x_fdma.c   | 60 ++++++++++++++++++-
+ 3 files changed, 61 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.c
+++ b/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.c
+@@ -354,6 +354,8 @@ static const struct sparx5_ops lan969x_o
+ 	.fdma_deinit             = &lan969x_fdma_deinit,
+ 	.fdma_poll               = &lan969x_fdma_napi_poll,
+ 	.fdma_xmit               = &lan969x_fdma_xmit,
+	.fdma_resize             = lan969x_fdma_resize,
+	.get_mtu                 = &sparx5_mtu_max,
+ };
+ 
+ const struct sparx5_match_data lan969x_desc = {
+--- a/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.h
+++ b/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x.h
+@@ -78,5 +78,6 @@ int lan969x_fdma_deinit(struct sparx5 *s
+ int lan969x_fdma_napi_poll(struct napi_struct *napi, int weight);
+ int lan969x_fdma_xmit(struct sparx5 *sparx5, u32 *ifh, struct sk_buff *skb,
+ 		      struct net_device *dev);
+int lan969x_fdma_resize(struct sparx5 *sparx5);
+ 
+ #endif
+--- a/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x_fdma.c
+++ b/drivers/net/ethernet/microchip/sparx5/lan969x/lan969x_fdma.c
+@@ -154,7 +154,7 @@ static int lan969x_fdma_rx_alloc(struct
+ 	int err;
+ 
+ 	struct page_pool_params pp_params = {
+-		.order = 0,
+		.order = rx->page_order,
+ 		.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
+ 		.pool_size = fdma->n_dcbs * fdma->n_dbs,
+ 		.nid = NUMA_NO_NODE,
+@@ -209,12 +209,14 @@ static void lan969x_fdma_rx_init(struct
+ {
+ 	struct fdma *fdma = &sparx5->rx.fdma;
+ 
+	sparx5->rx.page_order =
+		round_up(sparx5->tx.max_mtu, PAGE_SIZE) / PAGE_SIZE - 1;
+ 	fdma->channel_id = FDMA_XTR_CHANNEL;
+ 	fdma->n_dcbs = FDMA_DCB_MAX;
+ 	fdma->n_dbs = 1;
+ 	fdma->priv = sparx5;
+ 	fdma->size = fdma_get_size(fdma);
+-	fdma->db_size = PAGE_SIZE;
+	fdma->db_size = PAGE_SIZE << sparx5->rx.page_order;
+ 	fdma->ops.dataptr_cb = &lan969x_fdma_rx_dataptr_cb;
+ 	fdma->ops.nextptr_cb = &fdma_nextptr_cb;
+ 
+@@ -359,6 +361,8 @@ int lan969x_fdma_init(struct sparx5 *spa
+ 	struct sparx5_rx *rx = &sparx5->rx;
+ 	int err;
+ 
+	sparx5->tx.max_mtu = sparx5->data->ops->get_mtu(sparx5);
+
+ 	lan969x_fdma_rx_init(sparx5);
+ 	lan969x_fdma_tx_init(sparx5);
+ 	sparx5_fdma_injection_mode(sparx5);
+@@ -404,3 +408,55 @@ int lan969x_fdma_deinit(struct sparx5 *s
+ 
+ 	return 0;
+ }
+
+int lan969x_fdma_resize(struct sparx5 *sparx5)
+{
+	struct page_pool *page_pool_old = sparx5->rx.page_pool;
+	u32 old_mtu = sparx5->tx.max_mtu;
+	struct fdma tx_fdma_old = {0};
+	struct fdma rx_fdma_old = {0};
+	int err;
+
+	memcpy(&tx_fdma_old, &sparx5->tx.fdma, sizeof(struct fdma));
+	memcpy(&rx_fdma_old, &sparx5->rx.fdma, sizeof(struct fdma));
+
+	sparx5_fdma_stop(sparx5);
+	lan969x_fdma_free_pages(&sparx5->rx);
+
+	err = lan969x_fdma_init(sparx5);
+	if (err)
+		goto restore;
+
+	fdma_free_coherent(sparx5->dev, &rx_fdma_old);
+	fdma_free_coherent(sparx5->dev, &tx_fdma_old);
+	page_pool_destroy(page_pool_old);
+
+	goto start;
+
+restore:
+
+	/* At this point, the FDMA engine is stopped and the stack is not
+	 * calling us for xmit. Restore the old MTU and rx,tx buffers and
+	 * restart the engine.
+	 */
+
+	sparx5->tx.max_mtu = old_mtu;
+	sparx5->rx.page_pool = page_pool_old;
+	memcpy(&sparx5->tx.fdma, &tx_fdma_old, sizeof(struct fdma));
+	memcpy(&sparx5->rx.fdma, &rx_fdma_old, sizeof(struct fdma));
+
+	/* Old buffers have to be re-initialized. */
+
+	fdma_dcbs_init(&sparx5->rx.fdma,
+		       FDMA_DCB_INFO_DATAL(sparx5->rx.fdma.db_size),
+		       FDMA_DCB_STATUS_INTR);
+
+	fdma_dcbs_init(&sparx5->tx.fdma,
+		       FDMA_DCB_INFO_DATAL(sparx5->tx.fdma.db_size),
+		       FDMA_DCB_STATUS_DONE);
+
+start:
+	sparx5_fdma_start(sparx5);
+
+	return err;
+}
--- a/target/linux/microchipsw/patches-6.12/130-net-sparx5-wire-in-MTU-change.patch
+++ b/target/linux/microchipsw/patches-6.12/130-net-sparx5-wire-in-MTU-change.patch
@ -0,0 +1,33 @@
+From aa92b8a004be460d68aa671c3f8e98373496b199 Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko@sartura.hr>
+Date: Tue, 24 Mar 2026 12:32:39 +0100
+Subject: [PATCH 130/130] net: sparx5: wire in MTU change
+
+Now that both generic and chip specific MTU code is in place, add the
+required netdev OP to trigger the MTU change.
+
+Signed-off-by: Robert Marko <robert.marko@sartura.hr>
+---
+ drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
+@@ -259,6 +259,7 @@ static const struct net_device_ops sparx
+ 	.ndo_setup_tc           = sparx5_port_setup_tc,
+ 	.ndo_hwtstamp_get       = sparx5_port_hwtstamp_get,
+ 	.ndo_hwtstamp_set       = sparx5_port_hwtstamp_set,
+	.ndo_change_mtu		= sparx5_mtu_change,
+ };
+ 
+ bool sparx5_netdevice_check(const struct net_device *dev)
+@@ -279,6 +280,9 @@ struct net_device *sparx5_create_netdev(
+ 	ndev->hw_features |= NETIF_F_HW_TC;
+ 	ndev->features |= NETIF_F_HW_TC;
+ 
+	/* The MAC supports frame lengths of up to 14,000 bytes */
+	ndev->max_mtu = 14000;
+
+ 	SET_NETDEV_DEV(ndev, sparx5->dev);
+ 	spx5_port = netdev_priv(ndev);
+ 	spx5_port->ndev = ndev;