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>

2 files changed, 22 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index f9b04bc7e602..1f863a96a480 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -587,6 +587,10 @@ static int send_connect(struct c4iw_ep *ep)
                 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 @@ static void accept_cr(struct c4iw_ep *ep, struct sk_buff *skb,
                 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);
diff --git a/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h b/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
index dc193c292671..6121ca08fe58 100644
--- a/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
+++ b/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
@@ -836,4 +836,18 @@ struct ulptx_idata {
 #define V_RX_DACK_CHANGE(x) ((x) << S_RX_DACK_CHANGE)
 #define F_RX_DACK_CHANGE    V_RX_DACK_CHANGE(1U)
 
+enum {                     /* TCP congestion control algorithms */
+        CONG_ALG_RENO,
+        CONG_ALG_TAHOE,
+        CONG_ALG_NEWRENO,
+        CONG_ALG_HIGHSPEED
+};
+
+#define S_CONG_CNTRL    14
+#define M_CONG_CNTRL    0x3
+#define V_CONG_CNTRL(x) ((x) << S_CONG_CNTRL)
+#define G_CONG_CNTRL(x) (((x) >> S_CONG_CNTRL) & M_CONG_CNTRL)
+
+#define T5_OPT_2_VALID       (1 << 31)
+
 #endif /* _T4FW_RI_API_H_ */