VLAN-tagged interfaces on lan743x devices were previously unreachable via SSH and failed to respond to large ping packets (e.g. "ping -s 1469" given MTU=1500). In these scenarios, "ethtool -S" reports non-zero "RX Oversize Frame Errors". According to Microchip AN2948, the MAC_RX FSE (VLAN field size enforcement) bit determines whether frames with VLAN tags exceeding the base MTU plus tag length are discarded. The driver must set the MAC_RX.FSE bit before setting MAC_RX.RXEN to allow VLAN-tagged frames up to the interface MTU, preventing them from being treated as oversized. As a result, both the base and VLAN-tagged interfaces can use the same MTU without receive errors. Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver") Signed-off-by: David Thompson --- drivers/net/ethernet/microchip/lan743x_main.c | 2 ++ drivers/net/ethernet/microchip/lan743x_main.h | 1 + 2 files changed, 3 insertions(+) diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c index f3332417162e..6c840f8dd9c3 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -1266,6 +1266,8 @@ static int lan743x_mac_open(struct lan743x_adapter *adapter) u32 temp; temp = lan743x_csr_read(adapter, MAC_RX); + temp |= MAC_RX_FSE_; + lan743x_csr_write(adapter, MAC_RX, temp); lan743x_csr_write(adapter, MAC_RX, temp | MAC_RX_RXEN_); temp = lan743x_csr_read(adapter, MAC_TX); lan743x_csr_write(adapter, MAC_TX, temp | MAC_TX_TXEN_); diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h index 160d94a7cee6..1573c8f9c993 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.h +++ b/drivers/net/ethernet/microchip/lan743x_main.h @@ -182,6 +182,7 @@ #define MAC_RX (0x104) #define MAC_RX_MAX_SIZE_SHIFT_ (16) #define MAC_RX_MAX_SIZE_MASK_ (0x3FFF0000) +#define MAC_RX_FSE_ BIT(2) #define MAC_RX_RXD_ BIT(1) #define MAC_RX_RXEN_ BIT(0) -- 2.43.0