net: fec: add change_mtu to support dynamic buffer allocation

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.

Reviewed-by: Wei Fang <wei.fang@nxp.com>
Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
Link: https://patch.msgid.link/20250910185211.721341-6-shenwei.wang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index f1032a11aa7680df219d437329ba946bae9c5c3c..0127cfa5529f23f3f03113189d77f36126267e47 100644 (file)
--- 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 d71d0d4f5597176005d3f2cc076df909447f14dc..0e596681842b63d1edd944308edafc863925fec4 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -470,14 +470,14 @@ 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;
 
@@ -4025,6 +4025,23 @@ 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,
@@ -4034,6 +4051,7 @@ 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,