net: thunderx: Program LMAC credits based on MTU

Programming LMAC credits taking 9K frame size by default is incorrect
as for an interface which is one of the many on the same BGX/QLM
no of credits available will be less as Tx FIFO will be divided
across all interfaces. So let's say a BGX with 40G interface and another
BGX with multiple 10G, bandwidth of 10G interfaces will be effected when
traffic is running on both 40G and 10G interfaces simultaneously.

This patch fixes this issue by programming credits based on netdev's MTU.
Also fixed configuring MTU to HW and added CQE counter for pkts which
exceed this value.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/thunder/nic.h

@@ -47,7 +47,7 @@
 
 /* Min/Max packet size */
 #define	NIC_HW_MIN_FRS			64
-#define	NIC_HW_MAX_FRS			9200 /* 9216 max packet including FCS */
+#define	NIC_HW_MAX_FRS			9190 /* Excluding L2 header and FCS */
 
 /* Max pkinds */
 #define	NIC_MAX_PKIND			16
@@ -282,7 +282,6 @@ struct nicvf {
 
 	u8			node;
 	u8			cpi_alg;
-	u16			mtu;
 	bool			link_up;
 	u8			duplex;
 	u32			speed;

drivers/net/ethernet/cavium/thunder/nic_main.c

@@ -11,6 +11,7 @@
 #include <linux/pci.h>
 #include <linux/etherdevice.h>
 #include <linux/of.h>
+#include <linux/if_vlan.h>
 
 #include "nic_reg.h"
 #include "nic.h"
@@ -260,18 +261,31 @@ static void nic_get_bgx_stats(struct nicpf *nic, struct bgx_stats_msg *bgx)
 /* Update hardware min/max frame size */
 static int nic_update_hw_frs(struct nicpf *nic, int new_frs, int vf)
 {
-	if ((new_frs > NIC_HW_MAX_FRS) || (new_frs < NIC_HW_MIN_FRS)) {
-		dev_err(&nic->pdev->dev,
-			"Invalid MTU setting from VF%d rejected, should be between %d and %d\n",
-			   vf, NIC_HW_MIN_FRS, NIC_HW_MAX_FRS);
+	int bgx, lmac, lmac_cnt;
+	u64 lmac_credits;
+
+	if ((new_frs > NIC_HW_MAX_FRS) || (new_frs < NIC_HW_MIN_FRS))
 		return 1;
-	}
-	new_frs += ETH_HLEN;
-	if (new_frs <= nic->pkind.maxlen)
-		return 0;
 
-	nic->pkind.maxlen = new_frs;
-	nic_reg_write(nic, NIC_PF_PKIND_0_15_CFG, *(u64 *)&nic->pkind);
+	bgx = NIC_GET_BGX_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
+	lmac = NIC_GET_LMAC_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
+	lmac += bgx * MAX_LMAC_PER_BGX;
+
+	new_frs += VLAN_ETH_HLEN + ETH_FCS_LEN + 4;
+
+	/* Update corresponding LMAC credits */
+	lmac_cnt = bgx_get_lmac_count(nic->node, bgx);
+	lmac_credits = nic_reg_read(nic, NIC_PF_LMAC_0_7_CREDIT + (lmac * 8));
+	lmac_credits &= ~(0xFFFFFULL << 12);
+	lmac_credits |= (((((48 * 1024) / lmac_cnt) - new_frs) / 16) << 12);
+	nic_reg_write(nic, NIC_PF_LMAC_0_7_CREDIT + (lmac * 8), lmac_credits);
+
+	/* Enforce MTU in HW
+	 * This config is supported only from 88xx pass 2.0 onwards.
+	 */
+	if (!pass1_silicon(nic->pdev))
+		nic_reg_write(nic,
+			      NIC_PF_LMAC_0_7_CFG2 + (lmac * 8), new_frs);
 	return 0;
 }
 
@@ -464,7 +478,7 @@ static int nic_init_hw(struct nicpf *nic)
 
 	/* PKIND configuration */
 	nic->pkind.minlen = 0;
-	nic->pkind.maxlen = NIC_HW_MAX_FRS + ETH_HLEN;
+	nic->pkind.maxlen = NIC_HW_MAX_FRS + VLAN_ETH_HLEN + ETH_FCS_LEN + 4;
 	nic->pkind.lenerr_en = 1;
 	nic->pkind.rx_hdr = 0;
 	nic->pkind.hdr_sl = 0;

drivers/net/ethernet/cavium/thunder/nic_reg.h

@@ -106,6 +106,7 @@
 #define   NIC_PF_MPI_0_2047_CFG			(0x210000)
 #define   NIC_PF_RSSI_0_4097_RQ			(0x220000)
 #define   NIC_PF_LMAC_0_7_CFG			(0x240000)
+#define   NIC_PF_LMAC_0_7_CFG2			(0x240100)
 #define   NIC_PF_LMAC_0_7_SW_XOFF		(0x242000)
 #define   NIC_PF_LMAC_0_7_CREDIT		(0x244000)
 #define   NIC_PF_CHAN_0_255_TX_CFG		(0x400000)

drivers/net/ethernet/cavium/thunder/nicvf_main.c

@@ -1189,6 +1189,17 @@ int nicvf_stop(struct net_device *netdev)
 	return 0;
 }
 
+static int nicvf_update_hw_max_frs(struct nicvf *nic, int mtu)
+{
+	union nic_mbx mbx = {};
+
+	mbx.frs.msg = NIC_MBOX_MSG_SET_MAX_FRS;
+	mbx.frs.max_frs = mtu;
+	mbx.frs.vf_id = nic->vf_id;
+
+	return nicvf_send_msg_to_pf(nic, &mbx);
+}
+
 int nicvf_open(struct net_device *netdev)
 {
 	int err, qidx;
@@ -1196,8 +1207,6 @@ int nicvf_open(struct net_device *netdev)
 	struct queue_set *qs = nic->qs;
 	struct nicvf_cq_poll *cq_poll = NULL;
 
-	nic->mtu = netdev->mtu;
-
 	netif_carrier_off(netdev);
 
 	err = nicvf_register_misc_interrupt(nic);
@@ -1248,9 +1257,12 @@ int nicvf_open(struct net_device *netdev)
 	if (nic->sqs_mode)
 		nicvf_get_primary_vf_struct(nic);
 
-	/* Configure receive side scaling */
-	if (!nic->sqs_mode)
+	/* Configure receive side scaling and MTU */
+	if (!nic->sqs_mode) {
 		nicvf_rss_init(nic);
+		if (nicvf_update_hw_max_frs(nic, netdev->mtu))
+			goto cleanup;
+	}
 
 	err = nicvf_register_interrupts(nic);
 	if (err)
@@ -1297,17 +1309,6 @@ napi_del:
 	return err;
 }
 
-static int nicvf_update_hw_max_frs(struct nicvf *nic, int mtu)
-{
-	union nic_mbx mbx = {};
-
-	mbx.frs.msg = NIC_MBOX_MSG_SET_MAX_FRS;
-	mbx.frs.max_frs = mtu;
-	mbx.frs.vf_id = nic->vf_id;
-
-	return nicvf_send_msg_to_pf(nic, &mbx);
-}
-
 static int nicvf_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct nicvf *nic = netdev_priv(netdev);
@@ -1318,10 +1319,13 @@ static int nicvf_change_mtu(struct net_device *netdev, int new_mtu)
 	if (new_mtu < NIC_HW_MIN_FRS)
 		return -EINVAL;
 
+	netdev->mtu = new_mtu;
+
+	if (!netif_running(netdev))
+		return 0;
+
 	if (nicvf_update_hw_max_frs(nic, new_mtu))
 		return -EINVAL;
-	netdev->mtu = new_mtu;
-	nic->mtu = new_mtu;
 
 	return 0;
 }

drivers/net/ethernet/cavium/thunder/nicvf_queues.c

@@ -1530,6 +1530,9 @@ int nicvf_check_cqe_tx_errs(struct nicvf *nic,
 	case CQ_TX_ERROP_SUBDC_ERR:
 		stats->tx.subdesc_err++;
 		break;
+	case CQ_TX_ERROP_MAX_SIZE_VIOL:
+		stats->tx.max_size_exceeded++;
+		break;
 	case CQ_TX_ERROP_IMM_SIZE_OFLOW:
 		stats->tx.imm_size_oflow++;
 		break;

drivers/net/ethernet/cavium/thunder/nicvf_queues.h

@@ -158,6 +158,7 @@ enum CQ_TX_ERROP_E {
 	CQ_TX_ERROP_DESC_FAULT = 0x10,
 	CQ_TX_ERROP_HDR_CONS_ERR = 0x11,
 	CQ_TX_ERROP_SUBDC_ERR = 0x12,
+	CQ_TX_ERROP_MAX_SIZE_VIOL = 0x13,
 	CQ_TX_ERROP_IMM_SIZE_OFLOW = 0x80,
 	CQ_TX_ERROP_DATA_SEQUENCE_ERR = 0x81,
 	CQ_TX_ERROP_MEM_SEQUENCE_ERR = 0x82,
@@ -177,6 +178,7 @@ struct cmp_queue_stats {
 		u64 desc_fault;
 		u64 hdr_cons_err;
 		u64 subdesc_err;
+		u64 max_size_exceeded;
 		u64 imm_size_oflow;
 		u64 data_seq_err;
 		u64 mem_seq_err;