RDMA/nes: Fix interrupt moderation low threshold

Interrupt moderation low threshold value was incorrectly triggering,
indicating that the threshold should be lowered.

The impact was the timer was likely to become 40usecs and get stuck
there.  The biggest side effect was too many interrupts and nonoptimal
performance.

Signed-off-by: John Lacombe <jlacombe@neteffect.com>
Signed-off-by: Glenn Streiff <gstreiff@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 6 insertions, 9 deletions

diff --git a/drivers/infiniband/hw/nes/nes_hw.c b/drivers/infiniband/hw/nes/nes_hw.c
index 7c4c0fbf0ab..49e53e4c1eb 100644
--- a/drivers/infiniband/hw/nes/nes_hw.c
+++ b/drivers/infiniband/hw/nes/nes_hw.c
@@ -156,15 +156,14 @@ static void nes_nic_tune_timer(struct nes_device *nesdev)
 
         spin_lock_irqsave(&nesadapter->periodic_timer_lock, flags);
 
-        if (shared_timer->cq_count_old < cq_count) {
-                if (cq_count > shared_timer->threshold_low)
-                        shared_timer->cq_direction_downward=0;
-        }
-        if (shared_timer->cq_count_old >= cq_count)
+        if (shared_timer->cq_count_old <= cq_count)
+                shared_timer->cq_direction_downward = 0;
+        else
                 shared_timer->cq_direction_downward++;
         shared_timer->cq_count_old = cq_count;
         if (shared_timer->cq_direction_downward > NES_NIC_CQ_DOWNWARD_TREND) {
-                if (cq_count <= shared_timer->threshold_low) {
+                if (cq_count <= shared_timer->threshold_low &&
+                    shared_timer->threshold_low > 4) {
                         shared_timer->threshold_low = shared_timer->threshold_low/2;
                         shared_timer->cq_direction_downward=0;
                         nesdev->currcq_count = 0;
@@ -1728,7 +1727,6 @@ int nes_napi_isr(struct nes_device *nesdev)
                         nesdev->int_req &= ~NES_INT_TIMER;
                         nes_write32(nesdev->regs+NES_INTF_INT_MASK, ~(nesdev->intf_int_req));
                         nes_write32(nesdev->regs+NES_INT_MASK, ~nesdev->int_req);
-                        nesadapter->tune_timer.timer_in_use_old = 0;
                 }
                 nesdev->deepcq_count = 0;
                 return 1;
@@ -1867,7 +1865,6 @@ void nes_dpc(unsigned long param)
                                         nesdev->int_req &= ~NES_INT_TIMER;
                                         nes_write32(nesdev->regs + NES_INTF_INT_MASK, ~(nesdev->intf_int_req));
                                         nes_write32(nesdev->regs+NES_INT_MASK, ~nesdev->int_req);
-                                        nesdev->nesadapter->tune_timer.timer_in_use_old = 0;
                                 } else {
                                         nes_write32(nesdev->regs+NES_INT_MASK, 0x0000ffff|(~nesdev->int_req));
                                 }
diff --git a/drivers/infiniband/hw/nes/nes_hw.h b/drivers/infiniband/hw/nes/nes_hw.h
index 1e10df550c9..b7e2844f096 100644
--- a/drivers/infiniband/hw/nes/nes_hw.h
+++ b/drivers/infiniband/hw/nes/nes_hw.h
@@ -962,7 +962,7 @@ struct nes_arp_entry {
 #define DEFAULT_JUMBO_NES_QL_LOW    12
 #define DEFAULT_JUMBO_NES_QL_TARGET 40
 #define DEFAULT_JUMBO_NES_QL_HIGH   128
-#define NES_NIC_CQ_DOWNWARD_TREND   8
+#define NES_NIC_CQ_DOWNWARD_TREND   16
 
 struct nes_hw_tune_timer {
     //u16 cq_count;