[PATCH v5 net-next 3/5] net: fec: add rx_frame_size to support configurable RX length

[Shenwei Wang <shenwei.wang@nxp.com>]

Add a new rx_frame_size member in the fec_enet_private structure to
track the RX buffer size. On the Jumbo frame enabled system, the value
will be recalculated whenever the MTU is updated, allowing the driver
to allocate RX buffer efficiently.

Configure the MAX_FL (Maximum Frame Length) based on the current MTU,
by changing the OPT_FRAME_SIZE macro.

Configure the TRUNC_FL (Frame Truncation Length) based on the smaller
value between max_buf_size and the rx_frame_size to maintain consistent
RX error behavior, regardless of whether Jumbo frames are enabled.

Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
---
 drivers/net/ethernet/freescale/fec.h      | 1 +
 drivers/net/ethernet/freescale/fec_main.c | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 47317346b2f3..f1032a11aa76 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -621,6 +621,7 @@ struct fec_enet_private {
 	unsigned int total_rx_ring_size;
 	unsigned int max_buf_size;
 	unsigned int pagepool_order;
+	unsigned int rx_frame_size;
 
 	struct	platform_device *pdev;
 
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index f046d32a62fb..cf5118838f9c 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -253,7 +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	(fep->max_buf_size << 16)
+#define	OPT_FRAME_SIZE	((fep->netdev->mtu + ETH_HLEN + ETH_FCS_LEN) << 16)
 #else
 #define	OPT_FRAME_SIZE	0
 #endif
@@ -1191,7 +1191,7 @@ fec_restart(struct net_device *ndev)
 		else
 			val &= ~FEC_RACC_OPTIONS;
 		writel(val, fep->hwp + FEC_RACC);
-		writel(fep->max_buf_size, fep->hwp + FEC_FTRL);
+		writel(min(fep->rx_frame_size, fep->max_buf_size), fep->hwp + FEC_FTRL);
 	}
 #endif
 
@@ -4560,6 +4560,7 @@ fec_probe(struct platform_device *pdev)
 	pinctrl_pm_select_sleep_state(&pdev->dev);
 
 	fep->pagepool_order = 0;
+	fep->rx_frame_size = FEC_ENET_RX_FRSIZE;
 	fep->max_buf_size = PKT_MAXBUF_SIZE;
 	ndev->max_mtu = fep->max_buf_size - ETH_HLEN - ETH_FCS_LEN;
 
-- 
2.43.0