IB/ipath: Enable 4KB MTU

Enable use of 4KB MTU.  Since the driver uses more pinned memory for
receive buffers when the 4KB MTU is enabled, whether or not the fabric
supports that MTU, add a "mtu4096" module parameter that can be used to
limit the MTU to 2KB when it is known that 4KB MTUs can't be used
anyway.

Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 1 insertions, 6 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_verbs.c b/drivers/infiniband/hw/ipath/ipath_verbs.c
index 32d8f882e56c..012ccb4f9a37 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs.c
@@ -1201,12 +1201,7 @@ static int ipath_query_port(struct ib_device *ibdev,
         props->max_vl_num = 1;          /* VLCap = VL0 */
         props->init_type_reply = 0;
 
-        /*
-         * Note: the chip supports a maximum MTU of 4096, but the driver
-         * hasn't implemented this feature yet, so set the maximum value
-         * to 2048.
-         */
-        props->max_mtu = IB_MTU_2048;
+        props->max_mtu = ipath_mtu4096 ? IB_MTU_4096 : IB_MTU_2048;
         switch (dd->ipath_ibmtu) {
         case 4096:
                 mtu = IB_MTU_4096;