1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
index 2dd3aea05341..adcaf85355ae 100644
--- a/drivers/infiniband/hw/mthca/mthca_srq.c
+++ b/drivers/infiniband/hw/mthca/mthca_srq.c
@@ -192,7 +192,7 @@ int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
 
         /* Sanity check SRQ size before proceeding */
         if (attr->max_wr  > dev->limits.max_srq_wqes ||
-            attr->max_sge > dev->limits.max_sg)
+            attr->max_sge > dev->limits.max_srq_sge)
                 return -EINVAL;
 
         srq->max      = attr->max_wr;
@@ -660,6 +660,31 @@ int mthca_arbel_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
         return err;
 }
 
+int mthca_max_srq_sge(struct mthca_dev *dev)
+{
+        if (mthca_is_memfree(dev))
+                return dev->limits.max_sg;
+
+        /*
+         * SRQ allocations are based on powers of 2 for Tavor,
+         * (although they only need to be multiples of 16 bytes).
+         *
+         * Therefore, we need to base the max number of sg entries on
+         * the largest power of 2 descriptor size that is <= to the
+         * actual max WQE descriptor size, rather than return the
+         * max_sg value given by the firmware (which is based on WQE
+         * sizes as multiples of 16, not powers of 2).
+         *
+         * If SRQ implementation is changed for Tavor to be based on
+         * multiples of 16, the calculation below can be deleted and
+         * the FW max_sg value returned.
+         */
+        return min_t(int, dev->limits.max_sg,
+                     ((1 << (fls(dev->limits.max_desc_sz) - 1)) -
+                      sizeof (struct mthca_next_seg)) /
+                     sizeof (struct mthca_data_seg));
+}
+
 int __devinit mthca_init_srq_table(struct mthca_dev *dev)
 {
         int err;