IB/mthca: Avoid alignment traps when writing doorbells

Architectures such as ia64 see alignment traps when doing a 64-bit 
read from __be32 doorbell[2] arrays to do doorbell writes in 
mthca_write64().  Fix this by just passing the two halves of the 
doorbell value into mthca_write64().  This actually improves the 
generated code by allowing the compiler to see what's going on better.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 15 insertions, 30 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index df01b2026a64..0e5461c65731 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -1799,15 +1799,11 @@ int mthca_tavor_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 
 out:
         if (likely(nreq)) {
-                __be32 doorbell[2];
-
-                doorbell[0] = cpu_to_be32(((qp->sq.next_ind << qp->sq.wqe_shift) +
-                                           qp->send_wqe_offset) | f0 | op0);
-                doorbell[1] = cpu_to_be32((qp->qpn << 8) | size0);
-
                 wmb();
 
-                mthca_write64(doorbell,
+                mthca_write64(((qp->sq.next_ind << qp->sq.wqe_shift) +
+                               qp->send_wqe_offset) | f0 | op0,
+                              (qp->qpn << 8) | size0,
                               dev->kar + MTHCA_SEND_DOORBELL,
                               MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
                 /*
@@ -1829,7 +1825,6 @@ 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;
@@ -1907,13 +1902,10 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
                 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_write64((qp->rq.next_ind << qp->rq.wqe_shift) | size0,
+                                      qp->qpn << 8, dev->kar + MTHCA_RECEIVE_DOORBELL,
                                       MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
 
                         qp->rq.next_ind = ind;
@@ -1923,13 +1915,10 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 
 out:
         if (likely(nreq)) {
-                doorbell[0] = cpu_to_be32((qp->rq.next_ind << qp->rq.wqe_shift) | size0);
-                doorbell[1] = cpu_to_be32((qp->qpn << 8) | nreq);
-
                 wmb();
 
-                mthca_write64(doorbell,
-                              dev->kar + MTHCA_RECEIVE_DOORBELL,
+                mthca_write64((qp->rq.next_ind << qp->rq.wqe_shift) | size0,
+                              qp->qpn << 8 | nreq, dev->kar + MTHCA_RECEIVE_DOORBELL,
                               MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
         }
 
@@ -1951,7 +1940,7 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 {
         struct mthca_dev *dev = to_mdev(ibqp->device);
         struct mthca_qp *qp = to_mqp(ibqp);
-        __be32 doorbell[2];
+        u32 dbhi;
         void *wqe;
         void *prev_wqe;
         unsigned long flags;
@@ -1981,10 +1970,8 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                 if (unlikely(nreq == MTHCA_ARBEL_MAX_WQES_PER_SEND_DB)) {
                         nreq = 0;
 
-                        doorbell[0] = cpu_to_be32((MTHCA_ARBEL_MAX_WQES_PER_SEND_DB << 24) |
-                                                  ((qp->sq.head & 0xffff) << 8) |
-                                                  f0 | op0);
-                        doorbell[1] = cpu_to_be32((qp->qpn << 8) | size0);
+                        dbhi = (MTHCA_ARBEL_MAX_WQES_PER_SEND_DB << 24) |
+                                ((qp->sq.head & 0xffff) << 8) | f0 | op0;
 
                         qp->sq.head += MTHCA_ARBEL_MAX_WQES_PER_SEND_DB;
 
@@ -2000,7 +1987,8 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                          * write MMIO send doorbell.
                          */
                         wmb();
-                        mthca_write64(doorbell,
+
+                        mthca_write64(dbhi, (qp->qpn << 8) | size0,
                                       dev->kar + MTHCA_SEND_DOORBELL,
                                       MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
                 }
@@ -2154,10 +2142,7 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 
 out:
         if (likely(nreq)) {
-                doorbell[0] = cpu_to_be32((nreq << 24)                  |
-                                          ((qp->sq.head & 0xffff) << 8) |
-                                          f0 | op0);
-                doorbell[1] = cpu_to_be32((qp->qpn << 8) | size0);
+                dbhi = (nreq << 24) | ((qp->sq.head & 0xffff) << 8) | f0 | op0;
 
                 qp->sq.head += nreq;
 
@@ -2173,8 +2158,8 @@ out:
                  * write MMIO send doorbell.
                  */
                 wmb();
-                mthca_write64(doorbell,
-                              dev->kar + MTHCA_SEND_DOORBELL,
+
+                mthca_write64(dbhi, (qp->qpn << 8) | size0, dev->kar + MTHCA_SEND_DOORBELL,
                               MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
         }