[IB] mthca: fix posting long lists of receive work requests

In Tavor mode, when posting a long list of receive work requests, a
doorbell must be rung every 256 requests.  Add code to do this when
required.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

3 files changed, 39 insertions, 5 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index 190c1dc0ee27..760c418d5bc9 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -1707,6 +1707,7 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 {
         struct mthca_dev *dev = to_mdev(ibqp->device);
         struct mthca_qp *qp = to_mqp(ibqp);
+        __be32 doorbell[2];
         unsigned long flags;
         int err = 0;
         int nreq;
@@ -1724,6 +1725,22 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
         ind = qp->rq.next_ind;
 
         for (nreq = 0; wr; ++nreq, wr = wr->next) {
+                if (unlikely(nreq == MTHCA_TAVOR_MAX_WQES_PER_RECV_DB)) {
+                        nreq = 0;
+
+                        doorbell[0] = cpu_to_be32((qp->rq.next_ind << qp->rq.wqe_shift) | size0);
+                        doorbell[1] = cpu_to_be32(qp->qpn << 8);
+
+                        wmb();
+
+                        mthca_write64(doorbell,
+                                      dev->kar + MTHCA_RECEIVE_DOORBELL,
+                                      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
+
+                        qp->rq.head += MTHCA_TAVOR_MAX_WQES_PER_RECV_DB;
+                        size0 = 0;
+                }
+
                 if (mthca_wq_overflow(&qp->rq, nreq, qp->ibqp.recv_cq)) {
                         mthca_err(dev, "RQ %06x full (%u head, %u tail,"
                                         " %d max, %d nreq)\n", qp->qpn,
@@ -1781,8 +1798,6 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 
 out:
         if (likely(nreq)) {
-                __be32 doorbell[2];
-
                 doorbell[0] = cpu_to_be32((qp->rq.next_ind << qp->rq.wqe_shift) | size0);
                 doorbell[1] = cpu_to_be32((qp->qpn << 8) | nreq);
 
diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
index 292f55be8cbd..c3c0331a1f6e 100644
--- a/drivers/infiniband/hw/mthca/mthca_srq.c
+++ b/drivers/infiniband/hw/mthca/mthca_srq.c
@@ -414,6 +414,7 @@ int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
 {
         struct mthca_dev *dev = to_mdev(ibsrq->device);
         struct mthca_srq *srq = to_msrq(ibsrq);
+        __be32 doorbell[2];
         unsigned long flags;
         int err = 0;
         int first_ind;
@@ -429,6 +430,25 @@ int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
         first_ind = srq->first_free;
 
         for (nreq = 0; wr; ++nreq, wr = wr->next) {
+                if (unlikely(nreq == MTHCA_TAVOR_MAX_WQES_PER_RECV_DB)) {
+                        nreq = 0;
+
+                        doorbell[0] = cpu_to_be32(first_ind << srq->wqe_shift);
+                        doorbell[1] = cpu_to_be32(srq->srqn << 8);
+
+                        /*
+                         * Make sure that descriptors are written
+                         * before doorbell is rung.
+                         */
+                        wmb();
+
+                        mthca_write64(doorbell,
+                                      dev->kar + MTHCA_RECEIVE_DOORBELL,
+                                      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
+
+                        first_ind = srq->first_free;
+                }
+
                 ind = srq->first_free;
 
                 if (ind < 0) {
@@ -491,8 +511,6 @@ int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
         }
 
         if (likely(nreq)) {
-                __be32 doorbell[2];
-
                 doorbell[0] = cpu_to_be32(first_ind << srq->wqe_shift);
                 doorbell[1] = cpu_to_be32((srq->srqn << 8) | nreq);
 
diff --git a/drivers/infiniband/hw/mthca/mthca_wqe.h b/drivers/infiniband/hw/mthca/mthca_wqe.h
index 1f4c0ff28f79..73f1c0b9021e 100644
--- a/drivers/infiniband/hw/mthca/mthca_wqe.h
+++ b/drivers/infiniband/hw/mthca/mthca_wqe.h
@@ -49,7 +49,8 @@ enum {
 };
 
 enum {
-        MTHCA_INVAL_LKEY = 0x100
+        MTHCA_INVAL_LKEY                        = 0x100,
+        MTHCA_TAVOR_MAX_WQES_PER_RECV_DB        = 256
 };
 
 struct mthca_next_seg {