IB/qib: Eliminate divide/mod in converting idx to egr buf pointer

The context init now saves a shift from rcvegrbufs_perchunk
rcvegrbufs_perchunk_shift using ilog2.   A BUG_ON() protects the
power of 2 assumption.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/qib/qib_iba7220.c b/drivers/infiniband/hw/qib/qib_iba7220.c
index e1f947446c2a..3f1d562ba898 100644
--- a/drivers/infiniband/hw/qib/qib_iba7220.c
+++ b/drivers/infiniband/hw/qib/qib_iba7220.c
@@ -4085,6 +4085,8 @@ static int qib_init_7220_variables(struct qib_devdata *dd)
         /* we always allocate at least 2048 bytes for eager buffers */
         ret = ib_mtu_enum_to_int(qib_ibmtu);
         dd->rcvegrbufsize = ret != -1 ? max(ret, 2048) : QIB_DEFAULT_MTU;
+        BUG_ON(!is_power_of_2(dd->rcvegrbufsize));
+        dd->rcvegrbufsize_shift = ilog2(dd->rcvegrbufsize);
 
         qib_7220_tidtemplate(dd);