IB/ehca: Fix static rate if path faster than link

The formula would yield -1 if the path is faster than the link, which
is wrong in a bad way (max throttling).  Clamp to 0, which is the
correct value.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/hw/ehca/ehca_av.c b/drivers/infiniband/hw/ehca/ehca_av.c
index 453eb99..f7782c8 100644 (file)
--- a/drivers/infiniband/hw/ehca/ehca_av.c
+++ b/drivers/infiniband/hw/ehca/ehca_av.c
@@ -76,8 +76,12 @@ int ehca_calc_ipd(struct ehca_shca *shca, int port,
 
        link = ib_width_enum_to_int(pa.active_width) * pa.active_speed;
 
-       /* IPD = round((link / path) - 1) */
-       *ipd = ((link + (path >> 1)) / path) - 1;
+       if (path >= link)
+               /* no need to throttle if path faster than link */
+               *ipd = 0;
+       else
+               /* IPD = round((link / path) - 1) */
+               *ipd = ((link + (path >> 1)) / path) - 1;
 
        return 0;
 }