IB/ipath: Performance optimization for CPU differences

Different processors have different ordering restrictions for write
combining.  By taking advantage of this, we can eliminate some write
barriers when writing to the send buffers.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index 7a7966f..d983f92 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -724,6 +724,8 @@
 #define IPATH_LINKACTIVE    0x200
 		/* link current state is unknown */
 #define IPATH_LINKUNK       0x400
+		/* Write combining flush needed for PIO */
+#define IPATH_PIO_FLUSH_WC  0x1000
 		/* no IB cable, or no device on IB cable */
 #define IPATH_NOCABLE       0x4000
 		/* Supports port zero per packet receive interrupts via