From 510e35fb931ffc3b100e5d5ae4595cd3beca9f1a Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 9 Nov 2023 10:03:12 +0100 Subject: [PATCH 1/3] net: ethernet: cortina: Fix max RX frame define Enumerator 3 is 1548 bytes according to the datasheet. Not 1542. Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet") Reviewed-by: Andrew Lunn Signed-off-by: Linus Walleij Reviewed-by: Vladimir Oltean Link: https://lore.kernel.org/r/20231109-gemini-largeframe-fix-v4-1-6e611528db08@linaro.org Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cortina/gemini.c | 4 ++-- drivers/net/ethernet/cortina/gemini.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c index 5423fe26b4ef..562b0917316a 100644 --- a/drivers/net/ethernet/cortina/gemini.c +++ b/drivers/net/ethernet/cortina/gemini.c @@ -432,8 +432,8 @@ static const struct gmac_max_framelen gmac_maxlens[] = { .val = CONFIG0_MAXLEN_1536, }, { - .max_l3_len = 1542, - .val = CONFIG0_MAXLEN_1542, + .max_l3_len = 1548, + .val = CONFIG0_MAXLEN_1548, }, { .max_l3_len = 9212, diff --git a/drivers/net/ethernet/cortina/gemini.h b/drivers/net/ethernet/cortina/gemini.h index 9fdf77d5eb37..99efb1155743 100644 --- a/drivers/net/ethernet/cortina/gemini.h +++ b/drivers/net/ethernet/cortina/gemini.h @@ -787,7 +787,7 @@ union gmac_config0 { #define CONFIG0_MAXLEN_1536 0 #define CONFIG0_MAXLEN_1518 1 #define CONFIG0_MAXLEN_1522 2 -#define CONFIG0_MAXLEN_1542 3 +#define CONFIG0_MAXLEN_1548 3 #define CONFIG0_MAXLEN_9k 4 /* 9212 */ #define CONFIG0_MAXLEN_10k 5 /* 10236 */ #define CONFIG0_MAXLEN_1518__6 6 From d4d0c5b4d279bfe3585fbd806efefd3e51c82afa Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 9 Nov 2023 10:03:13 +0100 Subject: [PATCH 2/3] net: ethernet: cortina: Handle large frames The Gemini ethernet controller provides hardware checksumming for frames up to 1514 bytes including ethernet headers but not FCS. If we start sending bigger frames (after first bumping up the MTU on both interfaces sending and receiving the frames), truncated packets start to appear on the target such as in this tcpdump resulting from ping -s 1474: 23:34:17.241983 14:d6:4d:a8:3c:4f (oui Unknown) > bc:ae:c5:6b:a8:3d (oui Unknown), ethertype IPv4 (0x0800), length 1514: truncated-ip - 2 bytes missing! (tos 0x0, ttl 64, id 32653, offset 0, flags [DF], proto ICMP (1), length 1502) OpenWrt.lan > Fecusia: ICMP echo request, id 1672, seq 50, length 1482 If we bypass the hardware checksumming and provide a software fallback, everything starts working fine up to the max TX MTU of 2047 bytes, for example ping -s2000 192.168.1.2: 00:44:29.587598 bc:ae:c5:6b:a8:3d (oui Unknown) > 14:d6:4d:a8:3c:4f (oui Unknown), ethertype IPv4 (0x0800), length 2042: (tos 0x0, ttl 64, id 51828, offset 0, flags [none], proto ICMP (1), length 2028) Fecusia > OpenWrt.lan: ICMP echo reply, id 1683, seq 4, length 2008 The bit enabling to bypass hardware checksum (or any of the "TSS" bits) are undocumented in the hardware reference manual. The entire hardware checksum unit appears undocumented. The conclusion that we need to use the "bypass" bit was found by trial-and-error. Since no hardware checksum will happen, we slot in a software checksum fallback. Check for the condition where we need to compute checksum on the skb with either hardware or software using == CHECKSUM_PARTIAL instead of != CHECKSUM_NONE which is an incomplete check according to . On the D-Link DIR-685 router this fixes a bug on the conduit interface to the RTL8366RB DSA switch: as the switch needs to add space for its tag it increases the MTU on the conduit interface to 1504 and that means that when the router sends packages of 1500 bytes these get an extra 4 bytes of DSA tag and the transfer fails because of the erroneous hardware checksumming, affecting such basic functionality as the LuCI web interface. Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet") Signed-off-by: Linus Walleij Reviewed-by: Vladimir Oltean Link: https://lore.kernel.org/r/20231109-gemini-largeframe-fix-v4-2-6e611528db08@linaro.org Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cortina/gemini.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c index 562b0917316a..e5e73dee13ac 100644 --- a/drivers/net/ethernet/cortina/gemini.c +++ b/drivers/net/ethernet/cortina/gemini.c @@ -1145,6 +1145,7 @@ static int gmac_map_tx_bufs(struct net_device *netdev, struct sk_buff *skb, dma_addr_t mapping; unsigned short mtu; void *buffer; + int ret; mtu = ETH_HLEN; mtu += netdev->mtu; @@ -1159,9 +1160,30 @@ static int gmac_map_tx_bufs(struct net_device *netdev, struct sk_buff *skb, word3 |= mtu; } - if (skb->ip_summed != CHECKSUM_NONE) { + if (skb->len >= ETH_FRAME_LEN) { + /* Hardware offloaded checksumming isn't working on frames + * bigger than 1514 bytes. A hypothesis about this is that the + * checksum buffer is only 1518 bytes, so when the frames get + * bigger they get truncated, or the last few bytes get + * overwritten by the FCS. + * + * Just use software checksumming and bypass on bigger frames. + */ + if (skb->ip_summed == CHECKSUM_PARTIAL) { + ret = skb_checksum_help(skb); + if (ret) + return ret; + } + word1 |= TSS_BYPASS_BIT; + } else if (skb->ip_summed == CHECKSUM_PARTIAL) { int tcp = 0; + /* We do not switch off the checksumming on non TCP/UDP + * frames: as is shown from tests, the checksumming engine + * is smart enough to see that a frame is not actually TCP + * or UDP and then just pass it through without any changes + * to the frame. + */ if (skb->protocol == htons(ETH_P_IP)) { word1 |= TSS_IP_CHKSUM_BIT; tcp = ip_hdr(skb)->protocol == IPPROTO_TCP; From dc6c0bfbaa947dd7976e30e8c29b10c868b6fa42 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 9 Nov 2023 10:03:14 +0100 Subject: [PATCH 3/3] net: ethernet: cortina: Fix MTU max setting The RX max frame size is over 10000 for the Gemini ethernet, but the TX max frame size is actually just 2047 (0x7ff after checking the datasheet). Reflect this in what we offer to Linux, cap the MTU at the TX max frame minus ethernet headers. We delete the code disabling the hardware checksum for large MTUs as netdev->mtu can no longer be larger than netdev->max_mtu meaning the if()-clause in gmac_fix_features() is never true. Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet") Reviewed-by: Andrew Lunn Signed-off-by: Linus Walleij Reviewed-by: Vladimir Oltean Link: https://lore.kernel.org/r/20231109-gemini-largeframe-fix-v4-3-6e611528db08@linaro.org Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cortina/gemini.c | 17 ++++------------- drivers/net/ethernet/cortina/gemini.h | 2 +- 2 files changed, 5 insertions(+), 14 deletions(-) diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c index e5e73dee13ac..78287cfcbf63 100644 --- a/drivers/net/ethernet/cortina/gemini.c +++ b/drivers/net/ethernet/cortina/gemini.c @@ -2000,15 +2000,6 @@ static int gmac_change_mtu(struct net_device *netdev, int new_mtu) return 0; } -static netdev_features_t gmac_fix_features(struct net_device *netdev, - netdev_features_t features) -{ - if (netdev->mtu + ETH_HLEN + VLAN_HLEN > MTU_SIZE_BIT_MASK) - features &= ~GMAC_OFFLOAD_FEATURES; - - return features; -} - static int gmac_set_features(struct net_device *netdev, netdev_features_t features) { @@ -2234,7 +2225,6 @@ static const struct net_device_ops gmac_351x_ops = { .ndo_set_mac_address = gmac_set_mac_address, .ndo_get_stats64 = gmac_get_stats64, .ndo_change_mtu = gmac_change_mtu, - .ndo_fix_features = gmac_fix_features, .ndo_set_features = gmac_set_features, }; @@ -2486,11 +2476,12 @@ static int gemini_ethernet_port_probe(struct platform_device *pdev) netdev->hw_features = GMAC_OFFLOAD_FEATURES; netdev->features |= GMAC_OFFLOAD_FEATURES | NETIF_F_GRO; - /* We can handle jumbo frames up to 10236 bytes so, let's accept - * payloads of 10236 bytes minus VLAN and ethernet header + /* We can receive jumbo frames up to 10236 bytes but only + * transmit 2047 bytes so, let's accept payloads of 2047 + * bytes minus VLAN and ethernet header */ netdev->min_mtu = ETH_MIN_MTU; - netdev->max_mtu = 10236 - VLAN_ETH_HLEN; + netdev->max_mtu = MTU_SIZE_BIT_MASK - VLAN_ETH_HLEN; port->freeq_refill = 0; netif_napi_add(netdev, &port->napi, gmac_napi_poll); diff --git a/drivers/net/ethernet/cortina/gemini.h b/drivers/net/ethernet/cortina/gemini.h index 99efb1155743..24bb989981f2 100644 --- a/drivers/net/ethernet/cortina/gemini.h +++ b/drivers/net/ethernet/cortina/gemini.h @@ -502,7 +502,7 @@ union gmac_txdesc_3 { #define SOF_BIT 0x80000000 #define EOF_BIT 0x40000000 #define EOFIE_BIT BIT(29) -#define MTU_SIZE_BIT_MASK 0x1fff +#define MTU_SIZE_BIT_MASK 0x7ff /* Max MTU 2047 bytes */ /* GMAC Tx Descriptor */ struct gmac_txdesc {