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, 3 insertions, 7 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_iba6120.c b/drivers/infiniband/hw/ipath/ipath_iba6120.c
index 828066e20ad7..a9fc80409e57 100644
--- a/drivers/infiniband/hw/ipath/ipath_iba6120.c
+++ b/drivers/infiniband/hw/ipath/ipath_iba6120.c
@@ -1441,17 +1441,13 @@ static int ipath_pe_early_init(struct ipath_devdata *dd)
         dd->ipath_egrtidbase = (u64 __iomem *)
                 ((char __iomem *) dd->ipath_kregbase + dd->ipath_rcvegrbase);
 
-        /*
-         * To truly support a 4KB MTU (for usermode), we need to
-         * bump this to a larger value.  For now, we use them for
-         * the kernel only.
-         */
-        dd->ipath_rcvegrbufsize = 2048;
+        dd->ipath_rcvegrbufsize = ipath_mtu4096 ? 4096 : 2048;
         /*
          * the min() check here is currently a nop, but it may not always
          * be, depending on just how we do ipath_rcvegrbufsize
          */
-        dd->ipath_ibmaxlen = min(dd->ipath_piosize2k,
+        dd->ipath_ibmaxlen = min(ipath_mtu4096 ? dd->ipath_piosize4k :
+                                 dd->ipath_piosize2k,
                                  dd->ipath_rcvegrbufsize +
                                  (dd->ipath_rcvhdrentsize << 2));
         dd->ipath_init_ibmaxlen = dd->ipath_ibmaxlen;