[PATCH 10/13] IB/hfi1: Adjust hardware buffering parameter

Dennis Dalessandro
2016-09-25T14:42:01Z

From: Harish Chegondi <harish.chegondi-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

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

Reviewed-by: Dean Luick <dean.luick-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Harish Chegondi <harish.chegondi-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
drivers/infiniband/hw/hfi1/chip.c | 4 ++--
drivers/infiniband/hw/hfi1/chip.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index 26c5ee5..88394cd 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/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,
diff --git a/drivers/infiniband/hw/hfi1/chip.h b/drivers/infiniband/hw/hfi1/chip.h
index 92f2485..9234525 100644
--- a/drivers/infiniband/hw/hfi1/chip.h
+++ b/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