IB/hfi1: Adjust hardware buffering parameter

It was determined that 0x880 is a better value for hardware buffering,
use it.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/chip.c

@@ -13385,9 +13385,9 @@ static void init_rbufs(struct hfi1_devdata *dd)
 		/*
 		 * Give up after 1ms - maximum wait time.
 		 *
-		 * RBuf size is 148KiB.  Slowest possible is PCIe Gen1 x1 at
+		 * RBuf size is 136KiB.  Slowest possible is PCIe Gen1 x1 at
 		 * 250MB/s bandwidth.  Lower rate to 66% for overhead to get:
-		 *	148 KB / (66% * 250MB/s) = 920us
+		 *	136 KB / (66% * 250MB/s) = 844us
 		 */
 		if (count++ > 500) {
 			dd_dev_err(dd,

drivers/infiniband/hw/hfi1/chip.h

@@ -82,7 +82,7 @@
  */
 #define CM_VAU 3
 /* HFI link credit count, AKA receive buffer depth (RBUF_DEPTH) */
-#define CM_GLOBAL_CREDITS 0x940
+#define CM_GLOBAL_CREDITS 0x880
 /* Number of PKey entries in the HW */
 #define MAX_PKEY_VALUES 16