MFC r284988, r285220, and r285221.

r284988:
cxgbe(4): request an automatic tx update when a netmap tx queue idles.
The NIC tx queues already do this.

r285220:
cxgbe(4): Do not override the the global defaults for congestion drops.
The hw.cxgbe.cong_drop knob is not affected by this change because the
driver sets up congestion drop on a per-queue basis.

r285221:
cxgbe(4): Add a new knob that controls the congestion response of netmap
rx queues.  The default is to drop rather than backpressure.

This decouples the congestion settings of NIC and netmap rx queues.

3 files changed, 18 insertions, 25 deletions

diff --git a/sys/dev/cxgbe/adapter.h b/sys/dev/cxgbe/adapter.h
index 0ecdf07..f37d08b 100644
--- a/sys/dev/cxgbe/adapter.h
+++ b/sys/dev/cxgbe/adapter.h
@@ -1045,7 +1045,7 @@ void t4_update_fl_bufsize(struct ifnet *);
 int parse_pkt(struct mbuf **);
 void *start_wrq_wr(struct sge_wrq *, int, struct wrq_cookie *);
 void commit_wrq_wr(struct sge_wrq *, void *, struct wrq_cookie *);
-int tnl_cong(struct port_info *);
+int tnl_cong(struct port_info *, int);
 
 /* t4_tracer.c */
 struct t4_tracer;
diff --git a/sys/dev/cxgbe/t4_netmap.c b/sys/dev/cxgbe/t4_netmap.c
index c739146..f54a67f 100644
--- a/sys/dev/cxgbe/t4_netmap.c
+++ b/sys/dev/cxgbe/t4_netmap.c
@@ -77,6 +77,15 @@ int holdoff_tmr_idx = 2;
 SYSCTL_INT(_hw_cxgbe, OID_AUTO, nm_holdoff_tmr_idx, CTLFLAG_RWTUN,
     &holdoff_tmr_idx, 0, "Holdoff timer index for netmap rx queues.");
 
+/*
+ * Congestion drops.
+ * -1: no congestion feedback (not recommended).
+ *  0: backpressure the channel instead of dropping packets right away.
+ *  1: no backpressure, drop packets for the congested queue immediately.
+ */
+static int nm_cong_drop = 1;
+TUNABLE_INT("hw.cxgbe.nm_cong_drop", &nm_cong_drop);
+
 /* netmap ifnet routines */
 static void cxgbe_nm_init(void *);
 static int cxgbe_nm_ioctl(struct ifnet *, unsigned long, caddr_t);
@@ -405,8 +414,8 @@ alloc_nm_txq_hwq(struct port_info *pi, struct sge_nm_txq *nm_txq)
 	    V_FW_EQ_ETH_CMD_VFN(0));
 	c.alloc_to_len16 = htobe32(F_FW_EQ_ETH_CMD_ALLOC |
 	    F_FW_EQ_ETH_CMD_EQSTART | FW_LEN16(c));
-	c.autoequiqe_to_viid = htobe32(F_FW_EQ_ETH_CMD_AUTOEQUEQE |
-	    V_FW_EQ_ETH_CMD_VIID(pi->nm_viid));
+	c.autoequiqe_to_viid = htobe32(F_FW_EQ_ETH_CMD_AUTOEQUIQE |
+	    F_FW_EQ_ETH_CMD_AUTOEQUEQE | V_FW_EQ_ETH_CMD_VIID(pi->nm_viid));
 	c.fetchszm_to_iqid =
 	    htobe32(V_FW_EQ_ETH_CMD_HOSTFCMODE(X_HOSTFCMODE_NONE) |
 		V_FW_EQ_ETH_CMD_PCIECHN(pi->tx_chan) | F_FW_EQ_ETH_CMD_FETCHRO |
@@ -503,7 +512,7 @@ cxgbe_netmap_on(struct adapter *sc, struct port_info *pi, struct ifnet *ifp,
 	nm_set_native_flags(na);
 
 	for_each_nm_rxq(pi, i, nm_rxq) {
-		alloc_nm_rxq_hwq(pi, nm_rxq, tnl_cong(pi));
+		alloc_nm_rxq_hwq(pi, nm_rxq, tnl_cong(pi, nm_cong_drop));
 		nm_rxq->fl_hwidx = hwidx;
 		slot = netmap_reset(na, NR_RX, i, 0);
 		MPASS(slot != NULL);	/* XXXNM: error check, not assert */
diff --git a/sys/dev/cxgbe/t4_sge.c b/sys/dev/cxgbe/t4_sge.c
index a704a8d..5c7eb48 100644
--- a/sys/dev/cxgbe/t4_sge.c
+++ b/sys/dev/cxgbe/t4_sge.c
@@ -471,12 +471,6 @@ t4_tweak_chip_settings(struct adapter *sc)
 	    V_TIMERVALUE5(us_to_core_ticks(sc, intr_timer[5]));
 	t4_write_reg(sc, A_SGE_TIMER_VALUE_4_AND_5, v);
 
-	if (cong_drop == 0) {
-		m = F_TUNNELCNGDROP0 | F_TUNNELCNGDROP1 | F_TUNNELCNGDROP2 |
-		    F_TUNNELCNGDROP3;
-		t4_set_reg_field(sc, A_TP_PARA_REG3, m, 0);
-	}
-
 	/* 4K, 16K, 64K, 256K DDP "page sizes" */
 	v = V_HPZ0(0) | V_HPZ1(2) | V_HPZ2(4) | V_HPZ3(6);
 	t4_write_reg(sc, A_ULP_RX_TDDP_PSZ, v);
@@ -684,17 +678,6 @@ t4_read_chip_settings(struct adapter *sc)
 	s->timer_val[4] = G_TIMERVALUE4(r) / core_ticks_per_usec(sc);
 	s->timer_val[5] = G_TIMERVALUE5(r) / core_ticks_per_usec(sc);
 
-	if (cong_drop == 0) {
-		m = F_TUNNELCNGDROP0 | F_TUNNELCNGDROP1 | F_TUNNELCNGDROP2 |
-		    F_TUNNELCNGDROP3;
-		r = t4_read_reg(sc, A_TP_PARA_REG3);
-		if (r & m) {
-			device_printf(sc->dev,
-			    "invalid TP_PARA_REG3(0x%x)\n", r);
-			rc = EINVAL;
-		}
-	}
-
 	v = V_HPZ0(0) | V_HPZ1(2) | V_HPZ2(4) | V_HPZ3(6);
 	r = t4_read_reg(sc, A_ULP_RX_TDDP_PSZ);
 	if (r != v) {
@@ -2915,12 +2898,12 @@ free_mgmtq(struct adapter *sc)
 }
 
 int
-tnl_cong(struct port_info *pi)
+tnl_cong(struct port_info *pi, int drop)
 {
 
-	if (cong_drop == -1)
+	if (drop == -1)
 		return (-1);
-	else if (cong_drop == 1)
+	else if (drop == 1)
 		return (0);
 	else
 		return (pi->rx_chan_map);
@@ -2934,7 +2917,8 @@ alloc_rxq(struct port_info *pi, struct sge_rxq *rxq, int intr_idx, int idx,
 	struct sysctl_oid_list *children;
 	char name[16];
 
-	rc = alloc_iq_fl(pi, &rxq->iq, &rxq->fl, intr_idx, tnl_cong(pi));
+	rc = alloc_iq_fl(pi, &rxq->iq, &rxq->fl, intr_idx,
+	    tnl_cong(pi, cong_drop));
 	if (rc != 0)
 		return (rc);