Refactor code to support Jumbo frame functionality by adding a member
variable in the fec_enet_private structure to store PKT_MAXBUF_SIZE.

Remove the OPT_FRAME_SIZE and define a new macro OPT_ARCH_HAS_MAX_FL to
indicate architectures that support configurable maximum frame length.
And update the MAX_FL register value to max_buf_size when
OPT_ARCH_HAS_MAX_FL is defined.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Frank Li <frank.li@nxp.com>
Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
---
 drivers/net/ethernet/freescale/fec.h      |  1 +
 drivers/net/ethernet/freescale/fec_main.c | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 5c8fdcef759b..2969088dda09 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -619,6 +619,7 @@ struct fec_enet_private {

 	unsigned int total_tx_ring_size;
 	unsigned int total_rx_ring_size;
+	unsigned int max_buf_size;

 	struct	platform_device *pdev;

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 1383918f8a3f..9d348a8edf02 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -253,9 +253,7 @@ MODULE_PARM_DESC(macaddr, "FEC Ethernet MAC address");
 #if defined(CONFIG_M523x) || defined(CONFIG_M527x) || defined(CONFIG_M528x) || \
     defined(CONFIG_M520x) || defined(CONFIG_M532x) || defined(CONFIG_ARM) || \
     defined(CONFIG_ARM64)
-#define	OPT_FRAME_SIZE	(PKT_MAXBUF_SIZE << 16)
-#else
-#define	OPT_FRAME_SIZE	0
+#define	OPT_ARCH_HAS_MAX_FL
 #endif

 /* FEC MII MMFR bits definition */
@@ -1083,7 +1081,7 @@ static void fec_enet_enable_ring(struct net_device *ndev)
 	for (i = 0; i < fep->num_rx_queues; i++) {
 		rxq = fep->rx_queue[i];
 		writel(rxq->bd.dma, fep->hwp + FEC_R_DES_START(i));
-		writel(PKT_MAXBUF_SIZE, fep->hwp + FEC_R_BUFF_SIZE(i));
+		writel(fep->max_buf_size, fep->hwp + FEC_R_BUFF_SIZE(i));

 		/* enable DMA1/2 */
 		if (i)
@@ -1145,9 +1143,13 @@ static void
 fec_restart(struct net_device *ndev)
 {
 	struct fec_enet_private *fep = netdev_priv(ndev);
-	u32 rcntl = OPT_FRAME_SIZE | FEC_RCR_MII;
+	u32 rcntl = FEC_RCR_MII;
 	u32 ecntl = FEC_ECR_ETHEREN;

+#ifdef OPT_ARCH_HAS_MAX_FL
+	rcntl |= fep->max_buf_size << 16;
+#endif
+
 	if (fep->bufdesc_ex)
 		fec_ptp_save_state(fep);

@@ -1191,7 +1193,7 @@ fec_restart(struct net_device *ndev)
 		else
 			val &= ~FEC_RACC_OPTIONS;
 		writel(val, fep->hwp + FEC_RACC);
-		writel(PKT_MAXBUF_SIZE, fep->hwp + FEC_FTRL);
+		writel(fep->max_buf_size, fep->hwp + FEC_FTRL);
 	}
 #endif

@@ -4559,7 +4561,8 @@ fec_probe(struct platform_device *pdev)
 	fec_enet_clk_enable(ndev, false);
 	pinctrl_pm_select_sleep_state(&pdev->dev);

-	ndev->max_mtu = PKT_MAXBUF_SIZE - ETH_HLEN - ETH_FCS_LEN;
+	fep->max_buf_size = PKT_MAXBUF_SIZE;
+	ndev->max_mtu = fep->max_buf_size - ETH_HLEN - ETH_FCS_LEN;

 	ret = register_netdev(ndev);
 	if (ret)
--
2.43.0

On Mon,  8 Sep 2025 11:17:50 -0500 Shenwei Wang wrote:
> -#define	OPT_FRAME_SIZE	(PKT_MAXBUF_SIZE << 16)
> -#else
> -#define	OPT_FRAME_SIZE	0
> +#define	OPT_ARCH_HAS_MAX_FL
>  #endif

> +#ifdef OPT_ARCH_HAS_MAX_FL
> +	rcntl |= fep->max_buf_size << 16;
> +#endif

We try to avoid ifdefs inside C functions, they make compilation
coverage harder. Could you define OPT_ARCH_HAS_MAX_FL to 0 or 1
depending on the platform, and then use:

	if (OPT_ARCH_HAS_MAX_FL)
		rcntl |= fep->max_buf_size << 16;

The compiler will eliminate the condition if it's a constant,
but its slightly easier to read and lets the compiler see the code
regardless of the arch.