From 486c292230166c2d61701d3c984bf9143588ea28 Mon Sep 17 00:00:00 2001 From: Horatiu Vultur Date: Sun, 30 Oct 2022 22:36:34 +0100 Subject: [PATCH] net: lan966x: Fix the MTU calculation When the MTU was changed, the lan966x didn't take in consideration the L2 header and the FCS. So the HW was configured with a smaller value than what was desired. Therefore the correct value to configure the HW would be new_mtu + ETH_HLEN + ETH_FCS_LEN. The vlan tag is not considered here, because at the time when the blamed commit was added, there was no vlan filtering support. The vlan fix will be part of the next patch. Fixes: d28d6d2e37d1 ("net: lan966x: add port module support") Signed-off-by: Horatiu Vultur Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 2 +- drivers/net/ethernet/microchip/lan966x/lan966x_main.h | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c index be2fd03..b3070c3 100644 --- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c @@ -386,7 +386,7 @@ static int lan966x_port_change_mtu(struct net_device *dev, int new_mtu) int old_mtu = dev->mtu; int err; - lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(new_mtu), + lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(LAN966X_HW_MTU(new_mtu)), lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port)); dev->mtu = new_mtu; diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h index 9656071..4ec3399 100644 --- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h @@ -26,6 +26,8 @@ #define LAN966X_BUFFER_MEMORY (160 * 1024) #define LAN966X_BUFFER_MIN_SZ 60 +#define LAN966X_HW_MTU(mtu) ((mtu) + ETH_HLEN + ETH_FCS_LEN) + #define PGID_AGGR 64 #define PGID_SRC 80 #define PGID_ENTRIES 89 -- 2.7.4