IB/hfi1: Add functions to receive TID RDMA READ response

This patch adds the functions to receive TID RDMA READ response. The TID
resource information in the KDETH packet header will direct the hardware
to deliver the packet payload to the user buffer automatically and the
software will handle the packet header for the last packet of a segment
as all other packet headers are suppressed by default. The TID entries
will be freed when all packets for a segment have been received. This
patch also adds the functions to handle KDETH eflag errors, including
flow sequence and generation errors, when a TID RDMA READ response
packet is received . The flow sequence error can be recovered by software
checking of the flow sequence and will disappear when the hardware flow
is programmed with a new generation number.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

3 files changed, 529 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/hfi1/tid_rdma.c b/drivers/infiniband/hw/hfi1/tid_rdma.c
index 888954a79dac..da8b63ec0f8d 100644
--- a/drivers/infiniband/hw/hfi1/tid_rdma.c
+++ b/drivers/infiniband/hw/hfi1/tid_rdma.c
@@ -67,6 +67,8 @@ static u32 mask_generation(u32 a)
 #define TID_RDMA_DESTQP_FLOW_SHIFT      11
 #define TID_RDMA_DESTQP_FLOW_MASK       0x1f
 
+#define TID_FLOW_SW_PSN BIT(0)
+
 #define TID_OPFN_QP_CTXT_MASK 0xff
 #define TID_OPFN_QP_CTXT_SHIFT 56
 #define TID_OPFN_QP_KDETH_MASK 0xff
@@ -1620,6 +1622,34 @@ u64 hfi1_access_sw_tid_wait(const struct cntr_entry *entry,
 	return dd->verbs_dev.n_tidwait;
 }
 
+static struct tid_rdma_flow *
+__find_flow_ranged(struct tid_rdma_request *req, u16 head, u16 tail,
+		   u32 psn, u16 *fidx)
+{
+	for ( ; CIRC_CNT(head, tail, MAX_FLOWS);
+	      tail = CIRC_NEXT(tail, MAX_FLOWS)) {
+		struct tid_rdma_flow *flow = &req->flows[tail];
+		u32 spsn, lpsn;
+
+		spsn = full_flow_psn(flow, flow->flow_state.spsn);
+		lpsn = full_flow_psn(flow, flow->flow_state.lpsn);
+
+		if (cmp_psn(psn, spsn) >= 0 && cmp_psn(psn, lpsn) <= 0) {
+			if (fidx)
+				*fidx = tail;
+			return flow;
+		}
+	}
+	return NULL;
+}
+
+static struct tid_rdma_flow *find_flow(struct tid_rdma_request *req,
+				       u32 psn, u16 *fidx)
+{
+	return __find_flow_ranged(req, req->setup_head, req->clear_tail, psn,
+				  fidx);
+}
+
 /* TID RDMA READ functions */
 u32 hfi1_build_tid_rdma_read_packet(struct rvt_swqe *wqe,
 				    struct ib_other_headers *ohdr, u32 *bth1,
@@ -2193,3 +2223,494 @@ u32 hfi1_build_tid_rdma_read_resp(struct rvt_qp *qp, struct rvt_ack_entry *e,
 done:
 	return hdwords;
 }
+
+static inline struct tid_rdma_request *
+find_tid_request(struct rvt_qp *qp, u32 psn, enum ib_wr_opcode opcode)
+	__must_hold(&qp->s_lock)
+{
+	struct rvt_swqe *wqe;
+	struct tid_rdma_request *req = NULL;
+	u32 i, end;
+
+	end = qp->s_cur + 1;
+	if (end == qp->s_size)
+		end = 0;
+	for (i = qp->s_acked; i != end;) {
+		wqe = rvt_get_swqe_ptr(qp, i);
+		if (cmp_psn(psn, wqe->psn) >= 0 &&
+		    cmp_psn(psn, wqe->lpsn) <= 0) {
+			if (wqe->wr.opcode == opcode)
+				req = wqe_to_tid_req(wqe);
+			break;
+		}
+		if (++i == qp->s_size)
+			i = 0;
+	}
+
+	return req;
+}
+
+void hfi1_rc_rcv_tid_rdma_read_resp(struct hfi1_packet *packet)
+{
+	/* HANDLER FOR TID RDMA READ RESPONSE packet (Requestor side */
+
+	/*
+	 * 1. Find matching SWQE
+	 * 2. Check that the entire segment has been read.
+	 * 3. Remove HFI1_S_WAIT_TID_RESP from s_flags.
+	 * 4. Free the TID flow resources.
+	 * 5. Kick the send engine (hfi1_schedule_send())
+	 */
+	struct ib_other_headers *ohdr = packet->ohdr;
+	struct rvt_qp *qp = packet->qp;
+	struct hfi1_qp_priv *priv = qp->priv;
+	struct hfi1_ctxtdata *rcd = packet->rcd;
+	struct tid_rdma_request *req;
+	struct tid_rdma_flow *flow;
+	u32 opcode, aeth;
+	bool is_fecn;
+	unsigned long flags;
+	u32 kpsn, ipsn;
+
+	is_fecn = process_ecn(qp, packet);
+	kpsn = mask_psn(be32_to_cpu(ohdr->bth[2]));
+	aeth = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.aeth);
+	opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;
+
+	spin_lock_irqsave(&qp->s_lock, flags);
+	ipsn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_psn));
+	req = find_tid_request(qp, ipsn, IB_WR_TID_RDMA_READ);
+	if (unlikely(!req))
+		goto ack_op_err;
+
+	flow = &req->flows[req->clear_tail];
+	/* When header suppression is disabled */
+	if (cmp_psn(ipsn, flow->flow_state.ib_lpsn))
+		goto ack_done;
+	req->ack_pending--;
+	priv->pending_tid_r_segs--;
+	qp->s_num_rd_atomic--;
+	if ((qp->s_flags & RVT_S_WAIT_FENCE) &&
+	    !qp->s_num_rd_atomic) {
+		qp->s_flags &= ~(RVT_S_WAIT_FENCE |
+				 RVT_S_WAIT_ACK);
+		hfi1_schedule_send(qp);
+	}
+	if (qp->s_flags & RVT_S_WAIT_RDMAR) {
+		qp->s_flags &= ~(RVT_S_WAIT_RDMAR | RVT_S_WAIT_ACK);
+		hfi1_schedule_send(qp);
+	}
+
+	/* Release the tid resources */
+	hfi1_kern_exp_rcv_clear(req);
+
+	if (!do_rc_ack(qp, aeth, ipsn, opcode, 0, rcd))
+		goto ack_done;
+
+	/* If not done yet, build next read request */
+	if (++req->comp_seg >= req->total_segs) {
+		priv->tid_r_comp++;
+		req->state = TID_REQUEST_COMPLETE;
+	}
+
+	/*
+	 * Clear the hw flow under two conditions:
+	 * 1. This request is a sync point and it is complete;
+	 * 2. Current request is completed and there are no more requests.
+	 */
+	if ((req->state == TID_REQUEST_SYNC &&
+	     req->comp_seg == req->cur_seg) ||
+	    priv->tid_r_comp == priv->tid_r_reqs) {
+		hfi1_kern_clear_hw_flow(priv->rcd, qp);
+		if (req->state == TID_REQUEST_SYNC)
+			req->state = TID_REQUEST_ACTIVE;
+	}
+
+	hfi1_schedule_send(qp);
+	goto ack_done;
+
+ack_op_err:
+	/*
+	 * The test indicates that the send engine has finished its cleanup
+	 * after sending the request and it's now safe to put the QP into error
+	 * state. However, if the wqe queue is empty (qp->s_acked == qp->s_tail
+	 * == qp->s_head), it would be unsafe to complete the wqe pointed by
+	 * qp->s_acked here. Putting the qp into error state will safely flush
+	 * all remaining requests.
+	 */
+	if (qp->s_last == qp->s_acked)
+		rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
+
+ack_done:
+	spin_unlock_irqrestore(&qp->s_lock, flags);
+	if (is_fecn)
+		hfi1_send_rc_ack(packet, is_fecn);
+}
+
+void hfi1_kern_read_tid_flow_free(struct rvt_qp *qp)
+	__must_hold(&qp->s_lock)
+{
+	u32 n = qp->s_acked;
+	struct rvt_swqe *wqe;
+	struct tid_rdma_request *req;
+	struct hfi1_qp_priv *priv = qp->priv;
+
+	lockdep_assert_held(&qp->s_lock);
+	/* Free any TID entries */
+	while (n != qp->s_tail) {
+		wqe = rvt_get_swqe_ptr(qp, n);
+		if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
+			req = wqe_to_tid_req(wqe);
+			hfi1_kern_exp_rcv_clear_all(req);
+		}
+
+		if (++n == qp->s_size)
+			n = 0;
+	}
+	/* Free flow */
+	hfi1_kern_clear_hw_flow(priv->rcd, qp);
+}
+
+static bool tid_rdma_tid_err(struct hfi1_ctxtdata *rcd,
+			     struct hfi1_packet *packet, u8 rcv_type,
+			     u8 opcode)
+{
+	struct rvt_qp *qp = packet->qp;
+	u32 ipsn;
+	struct ib_other_headers *ohdr = packet->ohdr;
+
+	if (rcv_type >= RHF_RCV_TYPE_IB)
+		goto done;
+
+	spin_lock(&qp->s_lock);
+	/*
+	 * For TID READ response, error out QP after freeing the tid
+	 * resources.
+	 */
+	if (opcode == TID_OP(READ_RESP)) {
+		ipsn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_psn));
+		if (cmp_psn(ipsn, qp->s_last_psn) > 0 &&
+		    cmp_psn(ipsn, qp->s_psn) < 0) {
+			hfi1_kern_read_tid_flow_free(qp);
+			spin_unlock(&qp->s_lock);
+			rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
+			goto done;
+		}
+	}
+
+	spin_unlock(&qp->s_lock);
+done:
+	return true;
+}
+
+static void restart_tid_rdma_read_req(struct hfi1_ctxtdata *rcd,
+				      struct rvt_qp *qp, struct rvt_swqe *wqe)
+{
+	struct tid_rdma_request *req;
+	struct tid_rdma_flow *flow;
+
+	/* Start from the right segment */
+	qp->r_flags |= RVT_R_RDMAR_SEQ;
+	req = wqe_to_tid_req(wqe);
+	flow = &req->flows[req->clear_tail];
+	hfi1_restart_rc(qp, flow->flow_state.ib_spsn, 0);
+	if (list_empty(&qp->rspwait)) {
+		qp->r_flags |= RVT_R_RSP_SEND;
+		rvt_get_qp(qp);
+		list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
+	}
+}
+
+/*
+ * Handle the KDETH eflags for TID RDMA READ response.
+ *
+ * Return true if the last packet for a segment has been received and it is
+ * time to process the response normally; otherwise, return true.
+ *
+ * The caller must hold the packet->qp->r_lock and the rcu_read_lock.
+ */
+static bool handle_read_kdeth_eflags(struct hfi1_ctxtdata *rcd,
+				     struct hfi1_packet *packet, u8 rcv_type,
+				     u8 rte, u32 psn, u32 ibpsn)
+	__must_hold(&packet->qp->r_lock) __must_hold(RCU)
+{
+	struct hfi1_pportdata *ppd = rcd->ppd;
+	struct hfi1_devdata *dd = ppd->dd;
+	struct hfi1_ibport *ibp;
+	struct rvt_swqe *wqe;
+	struct tid_rdma_request *req;
+	struct tid_rdma_flow *flow;
+	u32 ack_psn;
+	struct rvt_qp *qp = packet->qp;
+	struct hfi1_qp_priv *priv = qp->priv;
+	bool ret = true;
+	int diff = 0;
+	u32 fpsn;
+
+	lockdep_assert_held(&qp->r_lock);
+	/* If the psn is out of valid range, drop the packet */
+	if (cmp_psn(ibpsn, qp->s_last_psn) < 0 ||
+	    cmp_psn(ibpsn, qp->s_psn) > 0)
+		return ret;
+
+	spin_lock(&qp->s_lock);
+	/*
+	 * Note that NAKs implicitly ACK outstanding SEND and RDMA write
+	 * requests and implicitly NAK RDMA read and atomic requests issued
+	 * before the NAK'ed request.
+	 */
+	ack_psn = ibpsn - 1;
+	wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
+	ibp = to_iport(qp->ibqp.device, qp->port_num);
+
+	/* Complete WQEs that the PSN finishes. */
+	while ((int)delta_psn(ack_psn, wqe->lpsn) >= 0) {
+		/*
+		 * If this request is a RDMA read or atomic, and the NACK is
+		 * for a later operation, this NACK NAKs the RDMA read or
+		 * atomic.
+		 */
+		if (wqe->wr.opcode == IB_WR_RDMA_READ ||
+		    wqe->wr.opcode == IB_WR_TID_RDMA_READ ||
+		    wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
+		    wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) {
+			/* Retry this request. */
+			if (!(qp->r_flags & RVT_R_RDMAR_SEQ)) {
+				qp->r_flags |= RVT_R_RDMAR_SEQ;
+				if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
+					restart_tid_rdma_read_req(rcd, qp,
+								  wqe);
+				} else {
+					hfi1_restart_rc(qp, qp->s_last_psn + 1,
+							0);
+					if (list_empty(&qp->rspwait)) {
+						qp->r_flags |= RVT_R_RSP_SEND;
+						rvt_get_qp(qp);
+						list_add_tail(/* wait */
+						   &qp->rspwait,
+						   &rcd->qp_wait_list);
+					}
+				}
+			}
+			/*
+			 * No need to process the NAK since we are
+			 * restarting an earlier request.
+			 */
+			break;
+		}
+
+		wqe = do_rc_completion(qp, wqe, ibp);
+		if (qp->s_acked == qp->s_tail)
+			break;
+	}
+
+	/* Handle the eflags for the request */
+	if (wqe->wr.opcode != IB_WR_TID_RDMA_READ)
+		goto s_unlock;
+
+	req = wqe_to_tid_req(wqe);
+	switch (rcv_type) {
+	case RHF_RCV_TYPE_EXPECTED:
+		switch (rte) {
+		case RHF_RTE_EXPECTED_FLOW_SEQ_ERR:
+			/*
+			 * On the first occurrence of a Flow Sequence error,
+			 * the flag TID_FLOW_SW_PSN is set.
+			 *
+			 * After that, the flow is *not* reprogrammed and the
+			 * protocol falls back to SW PSN checking. This is done
+			 * to prevent continuous Flow Sequence errors for any
+			 * packets that could be still in the fabric.
+			 */
+			flow = find_flow(req, psn, NULL);
+			if (!flow) {
+				/*
+				 * We can't find the IB PSN matching the
+				 * received KDETH PSN. The only thing we can
+				 * do at this point is report the error to
+				 * the QP.
+				 */
+				hfi1_kern_read_tid_flow_free(qp);
+				spin_unlock(&qp->s_lock);
+				rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
+				return ret;
+			}
+			if (priv->flow_state.flags & TID_FLOW_SW_PSN) {
+				diff = cmp_psn(psn,
+					       priv->flow_state.r_next_psn);
+				if (diff > 0) {
+					if (!(qp->r_flags & RVT_R_RDMAR_SEQ))
+						restart_tid_rdma_read_req(rcd,
+									  qp,
+									  wqe);
+
+					/* Drop the packet.*/
+					goto s_unlock;
+				} else if (diff < 0) {
+					/*
+					 * If a response packet for a restarted
+					 * request has come back, reset the
+					 * restart flag.
+					 */
+					if (qp->r_flags & RVT_R_RDMAR_SEQ)
+						qp->r_flags &=
+							~RVT_R_RDMAR_SEQ;
+
+					/* Drop the packet.*/
+					goto s_unlock;
+				}
+
+				/*
+				 * If SW PSN verification is successful and
+				 * this is the last packet in the segment, tell
+				 * the caller to process it as a normal packet.
+				 */
+				fpsn = full_flow_psn(flow,
+						     flow->flow_state.lpsn);
+				if (cmp_psn(fpsn, psn) == 0) {
+					ret = false;
+					if (qp->r_flags & RVT_R_RDMAR_SEQ)
+						qp->r_flags &=
+							~RVT_R_RDMAR_SEQ;
+				}
+				priv->flow_state.r_next_psn++;
+			} else {
+				u64 reg;
+				u32 last_psn;
+
+				/*
+				 * The only sane way to get the amount of
+				 * progress is to read the HW flow state.
+				 */
+				reg = read_uctxt_csr(dd, rcd->ctxt,
+						     RCV_TID_FLOW_TABLE +
+						     (8 * flow->idx));
+				last_psn = mask_psn(reg);
+
+				priv->flow_state.r_next_psn = last_psn;
+				priv->flow_state.flags |= TID_FLOW_SW_PSN;
+				/*
+				 * If no request has been restarted yet,
+				 * restart the current one.
+				 */
+				if (!(qp->r_flags & RVT_R_RDMAR_SEQ))
+					restart_tid_rdma_read_req(rcd, qp,
+								  wqe);
+			}
+
+			break;
+
+		case RHF_RTE_EXPECTED_FLOW_GEN_ERR:
+			/*
+			 * Since the TID flow is able to ride through
+			 * generation mismatch, drop this stale packet.
+			 */
+			break;
+
+		default:
+			break;
+		}
+		break;
+
+	case RHF_RCV_TYPE_ERROR:
+		switch (rte) {
+		case RHF_RTE_ERROR_OP_CODE_ERR:
+		case RHF_RTE_ERROR_KHDR_MIN_LEN_ERR:
+		case RHF_RTE_ERROR_KHDR_HCRC_ERR:
+		case RHF_RTE_ERROR_KHDR_KVER_ERR:
+		case RHF_RTE_ERROR_CONTEXT_ERR:
+		case RHF_RTE_ERROR_KHDR_TID_ERR:
+		default:
+			break;
+		}
+	default:
+		break;
+	}
+s_unlock:
+	spin_unlock(&qp->s_lock);
+	return ret;
+}
+
+bool hfi1_handle_kdeth_eflags(struct hfi1_ctxtdata *rcd,
+			      struct hfi1_pportdata *ppd,
+			      struct hfi1_packet *packet)
+{
+	struct hfi1_ibport *ibp = &ppd->ibport_data;
+	struct hfi1_devdata *dd = ppd->dd;
+	struct rvt_dev_info *rdi = &dd->verbs_dev.rdi;
+	u8 rcv_type = rhf_rcv_type(packet->rhf);
+	u8 rte = rhf_rcv_type_err(packet->rhf);
+	struct ib_header *hdr = packet->hdr;
+	struct ib_other_headers *ohdr = NULL;
+	int lnh = be16_to_cpu(hdr->lrh[0]) & 3;
+	u16 lid  = be16_to_cpu(hdr->lrh[1]);
+	u8 opcode;
+	u32 qp_num, psn, ibpsn;
+	struct rvt_qp *qp;
+	unsigned long flags;
+	bool ret = true;
+
+	if (packet->rhf & (RHF_VCRC_ERR | RHF_ICRC_ERR))
+		return ret;
+
+	packet->ohdr = &hdr->u.oth;
+	ohdr = packet->ohdr;
+	trace_input_ibhdr(rcd->dd, packet, !!(rhf_dc_info(packet->rhf)));
+
+	/* Get the destination QP number. */
+	qp_num = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_qp) &
+		RVT_QPN_MASK;
+	if (lid >= be16_to_cpu(IB_MULTICAST_LID_BASE))
+		goto drop;
+
+	psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
+	opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;
+
+	rcu_read_lock();
+	qp = rvt_lookup_qpn(rdi, &ibp->rvp, qp_num);
+	if (!qp)
+		goto rcu_unlock;
+
+	packet->qp = qp;
+
+	/* Check for valid receive state. */
+	spin_lock_irqsave(&qp->r_lock, flags);
+	if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
+		ibp->rvp.n_pkt_drops++;
+		goto r_unlock;
+	}
+
+	if (packet->rhf & RHF_TID_ERR) {
+		/* For TIDERR and RC QPs preemptively schedule a NAK */
+		u32 tlen = rhf_pkt_len(packet->rhf); /* in bytes */
+
+		/* Sanity check packet */
+		if (tlen < 24)
+			goto r_unlock;
+
+		/*
+		 * Check for GRH. We should never get packets with GRH in this
+		 * path.
+		 */
+		if (lnh == HFI1_LRH_GRH)
+			goto r_unlock;
+
+		if (tid_rdma_tid_err(rcd, packet, rcv_type, opcode))
+			goto r_unlock;
+	}
+
+	/* handle TID RDMA READ */
+	if (opcode == TID_OP(READ_RESP)) {
+		ibpsn = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_psn);
+		ibpsn = mask_psn(ibpsn);
+		ret = handle_read_kdeth_eflags(rcd, packet, rcv_type, rte, psn,
+					       ibpsn);
+	}
+
+r_unlock:
+	spin_unlock_irqrestore(&qp->r_lock, flags);
+rcu_unlock:
+	rcu_read_unlock();
+drop:
+	return ret;
+}
diff --git a/drivers/infiniband/hw/hfi1/tid_rdma.h b/drivers/infiniband/hw/hfi1/tid_rdma.h
index 01ded7c0c302..d428236aef68 100644
--- a/drivers/infiniband/hw/hfi1/tid_rdma.h
+++ b/drivers/infiniband/hw/hfi1/tid_rdma.h
@@ -177,6 +177,8 @@ static inline void trdma_clean_swqe(struct rvt_qp *qp, struct rvt_swqe *wqe)
 	__trdma_clean_swqe(qp, wqe);
 }
 
+void hfi1_kern_read_tid_flow_free(struct rvt_qp *qp);
+
 int hfi1_qp_priv_init(struct rvt_dev_info *rdi, struct rvt_qp *qp,
 		      struct ib_qp_init_attr *init_attr);
 void hfi1_qp_priv_tid_free(struct rvt_dev_info *rdi, struct rvt_qp *qp);
@@ -201,5 +203,9 @@ void hfi1_rc_rcv_tid_rdma_read_req(struct hfi1_packet *packet);
 u32 hfi1_build_tid_rdma_read_resp(struct rvt_qp *qp, struct rvt_ack_entry *e,
 				  struct ib_other_headers *ohdr, u32 *bth0,
 				  u32 *bth1, u32 *bth2, u32 *len, bool *last);
+void hfi1_rc_rcv_tid_rdma_read_resp(struct hfi1_packet *packet);
+bool hfi1_handle_kdeth_eflags(struct hfi1_ctxtdata *rcd,
+			      struct hfi1_pportdata *ppd,
+			      struct hfi1_packet *packet);
 
 #endif /* HFI1_TID_RDMA_H */
diff --git a/drivers/infiniband/hw/hfi1/verbs.h b/drivers/infiniband/hw/hfi1/verbs.h
index 5e910c508360..c1574c0ed9a7 100644
--- a/drivers/infiniband/hw/hfi1/verbs.h
+++ b/drivers/infiniband/hw/hfi1/verbs.h
@@ -172,6 +172,8 @@ struct hfi1_qp_priv {
 	unsigned long tid_timer_timeout_jiffies;
 
 	/* For TID RDMA READ */
+	u32 tid_r_reqs;         /* Num of tid reads requested */
+	u32 tid_r_comp;         /* Num of tid reads completed */
 	u32 pending_tid_r_segs; /* Num of pending tid read segments */
 	u16 pkts_ps;            /* packets per segment */
 	u8 timeout_shift;       /* account for number of packets per segment */