Add a fec_change_mtu() handler to recalculate the pagepool_order based on
the new_mtu value. And update the rx_frame_size accordingly when
pagepool_order changes.

MTU changes are only allowed when the adater is not running.

Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
---
 drivers/net/ethernet/freescale/fec.h      |  5 +++--
 drivers/net/ethernet/freescale/fec_main.c | 22 ++++++++++++++++++++--
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index f1032a11aa76..0127cfa5529f 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -348,10 +348,11 @@ struct bufdesc_ex {
  * the skbuffer directly.
  */
 
+#define FEC_DRV_RESERVE_SPACE (XDP_PACKET_HEADROOM + \
+		SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 #define FEC_ENET_XDP_HEADROOM	(XDP_PACKET_HEADROOM)
 #define FEC_ENET_RX_PAGES	256
-#define FEC_ENET_RX_FRSIZE	(PAGE_SIZE - FEC_ENET_XDP_HEADROOM \
-		- SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
+#define FEC_ENET_RX_FRSIZE	(PAGE_SIZE - FEC_DRV_RESERVE_SPACE)
 #define FEC_ENET_RX_FRPPG	(PAGE_SIZE / FEC_ENET_RX_FRSIZE)
 #define RX_RING_SIZE		(FEC_ENET_RX_FRPPG * FEC_ENET_RX_PAGES)
 #define FEC_ENET_TX_FRSIZE	2048
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index df8b69af5296..a2aa08afa4bd 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -468,14 +468,14 @@ fec_enet_create_page_pool(struct fec_enet_private *fep,
 {
 	struct bpf_prog *xdp_prog = READ_ONCE(fep->xdp_prog);
 	struct page_pool_params pp_params = {
-		.order = 0,
+		.order = fep->pagepool_order,
 		.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
 		.pool_size = size,
 		.nid = dev_to_node(&fep->pdev->dev),
 		.dev = &fep->pdev->dev,
 		.dma_dir = xdp_prog ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE,
 		.offset = FEC_ENET_XDP_HEADROOM,
-		.max_len = FEC_ENET_RX_FRSIZE,
+		.max_len = fep->rx_frame_size,
 	};
 	int err;
 
@@ -4022,6 +4022,23 @@ static int fec_hwtstamp_set(struct net_device *ndev,
 	return fec_ptp_set(ndev, config, extack);
 }
 
+static int fec_change_mtu(struct net_device *ndev, int new_mtu)
+{
+	struct fec_enet_private *fep = netdev_priv(ndev);
+	int order;
+
+	if (netif_running(ndev))
+		return -EBUSY;
+
+	order = get_order(new_mtu + ETH_HLEN + ETH_FCS_LEN
+			  + FEC_DRV_RESERVE_SPACE);
+	fep->rx_frame_size = (PAGE_SIZE << order) - FEC_DRV_RESERVE_SPACE;
+	fep->pagepool_order = order;
+	WRITE_ONCE(ndev->mtu, new_mtu);
+
+	return 0;
+}
+
 static const struct net_device_ops fec_netdev_ops = {
 	.ndo_open		= fec_enet_open,
 	.ndo_stop		= fec_enet_close,
@@ -4031,6 +4048,7 @@ static const struct net_device_ops fec_netdev_ops = {
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_tx_timeout		= fec_timeout,
 	.ndo_set_mac_address	= fec_set_mac_address,
+	.ndo_change_mtu		= fec_change_mtu,
 	.ndo_eth_ioctl		= phy_do_ioctl_running,
 	.ndo_set_features	= fec_set_features,
 	.ndo_bpf		= fec_enet_bpf,
-- 
2.43.0