cxgbei: Use hardware RX flow control for offloaded iSCSI connections.

[jhb]

Summary

Forthcoming T6 iSCSI DDP support requires hardware RX flow control.

sys/dev/cxgbe/cxgbei/cxgbei.c

 #ifdef INVARIANTS
                 toep->ulpcb2 = NULL;
 #endif
                 return (0);
         }
 
         tp = intotcpcb(inp);
         MPASS(icp->icp_seq == tp->rcv_nxt);
-        MPASS(tp->rcv_wnd >= pdu_len);
         tp->rcv_nxt += pdu_len;
-        tp->rcv_wnd -= pdu_len;
         tp->t_rcvtime = ticks;
 
-        /* update rx credits */
-        t4_rcvd(&toep->td->tod, tp);        /* XXX: sc->tom_softc.tod */
+        /*
+         * Don't update the window size or return credits since RX
+         * flow control is disabled.
+         */
 
         so = inp->inp_socket;
         sb = &so->so_rcv;
         SOCKBUF_LOCK(sb);
 
         icc = toep->ulpcb;
         if (__predict_false(icc == NULL || sb->sb_state & SBS_CANTRCVMORE)) {
                 CTR5(KTR_CXGBE,

sys/dev/cxgbe/cxgbei/icl_cxgbei.c

set_ulp_mode_iscsi(struct adapter *sc, struct toepcb *toep, u_int ulp_submode)
 
         CTR3(KTR_CXGBE, "%s: tid %u, ULP_MODE_ISCSI, submode=%#x",
             __func__, toep->tid, ulp_submode);
 
         val = V_TCB_ULP_TYPE(ULP_MODE_ISCSI) | V_TCB_ULP_RAW(ulp_submode);
         t4_set_tcb_field(sc, toep->ctrlq, toep, W_TCB_ULP_TYPE,
             V_TCB_ULP_TYPE(M_TCB_ULP_TYPE) | V_TCB_ULP_RAW(M_TCB_ULP_RAW), val,
             0, 0);
+
+        val = V_TF_RX_FLOW_CONTROL_DISABLE(1ULL);
+        t4_set_tcb_field(sc, toep->ctrlq, toep, W_TCB_T_FLAGS, val, val, 0, 0);
 }
 
 /*
  * XXXNP: Who is responsible for cleaning up the socket if this returns with an
  * error?  Review all error paths.
  *
  * XXXNP: What happens to the socket's fd reference if the operation is
  * successful, and how does that affect the socket's life cycle?