[PATCH net] net: airoha: Fix max TX packet length configuration

[Lorenzo Bianconi <lorenzo@kernel.org>]

According to the Airoha documentation, REG_GDM_LEN_CFG() register does not
include FCS length. Fix MTU configuration removing ETH_FCS_LEN from
maximum TX packet length configuration.

Fixes: 54d989d58d2ac ("net: airoha: Move min/max packet len configuration in airoha_dev_open()")
Fixes: 03b1b69f0662c ("net: airoha: Introduce airoha_dev_change_mtu callback")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/airoha/airoha_eth.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index c14cdce588a7..a81ffda72b39 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -1629,9 +1629,9 @@ static void airoha_update_hw_stats(struct airoha_gdm_port *port)
 
 static int airoha_dev_open(struct net_device *dev)
 {
-	int err, len = ETH_HLEN + dev->mtu + ETH_FCS_LEN;
 	struct airoha_gdm_port *port = netdev_priv(dev);
 	struct airoha_qdma *qdma = port->qdma;
+	int err, len = ETH_HLEN + dev->mtu;
 
 	netif_tx_start_all_queues(dev);
 	err = airoha_set_vip_for_gdm_port(port, true);
@@ -1833,7 +1833,7 @@ static int airoha_dev_change_mtu(struct net_device *dev, int mtu)
 {
 	struct airoha_gdm_port *port = netdev_priv(dev);
 	struct airoha_eth *eth = port->qdma->eth;
-	u32 len = ETH_HLEN + mtu + ETH_FCS_LEN;
+	u32 len = ETH_HLEN + mtu;
 
 	airoha_fe_rmw(eth, REG_GDM_LEN_CFG(port->id),
 		      GDM_LONG_LEN_MASK,

---
base-commit: 02f72964395911e7a09bb2ea2fe6f79eda4ea2c2
change-id: 20260412-airoha-fix-max-mtu-f9c7823ce2a2

Best regards,
-- 
Lorenzo Bianconi <lorenzo@kernel.org>