IB/mthca: Fix max_srq_sge returned by ib_query_device for Tavor devices

[linux-block.git] / drivers / infiniband / hw / mthca / mthca_srq.c

diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
index 2dd3aea053415be7ce18ddf1186a6b32afceb462..adcaf85355ae6a33adb03dabb09c37f3ec85f0d3 100644 (file)
--- 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;