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>

drivers/infiniband/hw/mthca/mthca_cq.c

@@ -204,16 +204,11 @@ static void dump_cqe(struct mthca_dev *dev, void *cqe_ptr)
 static inline void update_cons_index(struct mthca_dev *dev, struct mthca_cq *cq,
 				     int incr)
 {
-	__be32 doorbell[2];
-
 	if (mthca_is_memfree(dev)) {
 		*cq->set_ci_db = cpu_to_be32(cq->cons_index);
 		wmb();
 	} else {
-		doorbell[0] = cpu_to_be32(MTHCA_TAVOR_CQ_DB_INC_CI | cq->cqn);
-		doorbell[1] = cpu_to_be32(incr - 1);
-
-		mthca_write64(doorbell,
+		mthca_write64(MTHCA_TAVOR_CQ_DB_INC_CI | cq->cqn, incr - 1,
 			      dev->kar + MTHCA_CQ_DOORBELL,
 			      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
 		/*
@@ -731,17 +726,12 @@ repoll:
 
 int mthca_tavor_arm_cq(struct ib_cq *cq, enum ib_cq_notify_flags flags)
 {
-	__be32 doorbell[2];
+	u32 dbhi = ((flags & IB_CQ_SOLICITED_MASK) == IB_CQ_SOLICITED ?
+		    MTHCA_TAVOR_CQ_DB_REQ_NOT_SOL :
+		    MTHCA_TAVOR_CQ_DB_REQ_NOT) |
+		to_mcq(cq)->cqn;
 
-	doorbell[0] = cpu_to_be32(((flags & IB_CQ_SOLICITED_MASK) ==
-				   IB_CQ_SOLICITED ?
-				   MTHCA_TAVOR_CQ_DB_REQ_NOT_SOL :
-				   MTHCA_TAVOR_CQ_DB_REQ_NOT)      |
-				  to_mcq(cq)->cqn);
-	doorbell[1] = (__force __be32) 0xffffffff;
-
-	mthca_write64(doorbell,
-		      to_mdev(cq->device)->kar + MTHCA_CQ_DOORBELL,
+	mthca_write64(dbhi, 0xffffffff, to_mdev(cq->device)->kar + MTHCA_CQ_DOORBELL,
 		      MTHCA_GET_DOORBELL_LOCK(&to_mdev(cq->device)->doorbell_lock));
 
 	return 0;
@@ -750,19 +740,16 @@ int mthca_tavor_arm_cq(struct ib_cq *cq, enum ib_cq_notify_flags flags)
 int mthca_arbel_arm_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags flags)
 {
 	struct mthca_cq *cq = to_mcq(ibcq);
-	__be32 doorbell[2];
-	u32 sn;
-	__be32 ci;
+	__be32 db_rec[2];
+	u32 dbhi;
+	u32 sn = cq->arm_sn & 3;
 
-	sn = cq->arm_sn & 3;
-	ci = cpu_to_be32(cq->cons_index);
+	db_rec[0] = cpu_to_be32(cq->cons_index);
+	db_rec[1] = cpu_to_be32((cq->cqn << 8) | (2 << 5) | (sn << 3) |
+				((flags & IB_CQ_SOLICITED_MASK) ==
+				 IB_CQ_SOLICITED ? 1 : 2));
 
-	doorbell[0] = ci;
-	doorbell[1] = cpu_to_be32((cq->cqn << 8) | (2 << 5) | (sn << 3) |
-				  ((flags & IB_CQ_SOLICITED_MASK) ==
-				   IB_CQ_SOLICITED ? 1 : 2));
-
-	mthca_write_db_rec(doorbell, cq->arm_db);
+	mthca_write_db_rec(db_rec, cq->arm_db);
 
 	/*
 	 * Make sure that the doorbell record in host memory is
@@ -770,14 +757,12 @@ int mthca_arbel_arm_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags flags)
 	 */
 	wmb();
 
-	doorbell[0] = cpu_to_be32((sn << 28)                       |
-				  ((flags & IB_CQ_SOLICITED_MASK) == IB_CQ_SOLICITED ?
-				   MTHCA_ARBEL_CQ_DB_REQ_NOT_SOL :
-				   MTHCA_ARBEL_CQ_DB_REQ_NOT)      |
-				  cq->cqn);
-	doorbell[1] = ci;
+	dbhi = (sn << 28) |
+		((flags & IB_CQ_SOLICITED_MASK) == IB_CQ_SOLICITED ?
+		 MTHCA_ARBEL_CQ_DB_REQ_NOT_SOL :
+		 MTHCA_ARBEL_CQ_DB_REQ_NOT) | cq->cqn;
 
-	mthca_write64(doorbell,
+	mthca_write64(dbhi, cq->cons_index,
 		      to_mdev(ibcq->device)->kar + MTHCA_CQ_DOORBELL,
 		      MTHCA_GET_DOORBELL_LOCK(&to_mdev(ibcq->device)->doorbell_lock));