RDMA/cxgb4: Force T5 connections to use TAHOE congestion control

This is required to work around a T5 HW issue.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index f9b04bc..1f863a9 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -587,6 +587,10 @@
 		opt2 |= SACK_EN(1);
 	if (wscale && enable_tcp_window_scaling)
 		opt2 |= WND_SCALE_EN(1);
+	if (is_t5(ep->com.dev->rdev.lldi.adapter_type)) {
+		opt2 |= T5_OPT_2_VALID;
+		opt2 |= V_CONG_CNTRL(CONG_ALG_TAHOE);
+	}
 	t4_set_arp_err_handler(skb, NULL, act_open_req_arp_failure);
 
 	if (is_t4(ep->com.dev->rdev.lldi.adapter_type)) {
@@ -2018,6 +2022,10 @@
 		if (tcph->ece && tcph->cwr)
 			opt2 |= CCTRL_ECN(1);
 	}
+	if (is_t5(ep->com.dev->rdev.lldi.adapter_type)) {
+		opt2 |= T5_OPT_2_VALID;
+		opt2 |= V_CONG_CNTRL(CONG_ALG_TAHOE);
+	}
 
 	rpl = cplhdr(skb);
 	INIT_TP_WR(rpl, ep->hwtid);