[PATCH 4/9] net/igb: Fix interrupt throttling interval calculation

[Nicholas Piggin <npiggin@gmail.com>]

IGB throttling granularity is 1us, and interval field is in bits 2..14
of the EITRx registers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/net/igb_regs.h | 3 +++
 hw/net/igb_core.c | 7 ++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/hw/net/igb_regs.h b/hw/net/igb_regs.h
index 4dc4c31da27..1ed5ee5039a 100644
--- a/hw/net/igb_regs.h
+++ b/hw/net/igb_regs.h
@@ -146,6 +146,9 @@ union e1000_adv_rx_desc {
 #define IGB_82576_VF_DEV_ID        0x10CA
 #define IGB_I350_VF_DEV_ID         0x1520
 
+/* Delay increments in nanoseconds for interrupt throttling registers */
+#define IGB_INTR_THROTTLING_NS_RES (1000)
+
 /* VLAN info */
 #define IGB_TX_FLAGS_VLAN_MASK     0xffff0000
 #define IGB_TX_FLAGS_VLAN_SHIFT    16
diff --git a/hw/net/igb_core.c b/hw/net/igb_core.c
index 39e3ce1c8fe..94f9785749a 100644
--- a/hw/net/igb_core.c
+++ b/hw/net/igb_core.c
@@ -142,8 +142,9 @@ static void igb_msix_notify(IGBCore *core, unsigned int cause)
 static inline void
 igb_intrmgr_rearm_timer(IGBIntrDelayTimer *timer)
 {
-    int64_t delay_ns = (int64_t) timer->core->mac[timer->delay_reg] *
-                                 timer->delay_resolution_ns;
+    int64_t delay_ns =
+            (int64_t)((timer->core->mac[timer->delay_reg] & 0x7FFC) >> 2) *
+                     timer->delay_resolution_ns;
 
     trace_e1000e_irq_rearm_timer(timer->delay_reg << 2, delay_ns);
 
@@ -180,7 +181,7 @@ igb_intrmgr_initialize_all_timers(IGBCore *core, bool create)
     for (i = 0; i < IGB_INTR_NUM; i++) {
         core->eitr[i].core = core;
         core->eitr[i].delay_reg = EITR0 + i;
-        core->eitr[i].delay_resolution_ns = E1000_INTR_DELAY_NS_RES;
+        core->eitr[i].delay_resolution_ns = IGB_INTR_THROTTLING_NS_RES;
     }
 
     if (!create) {
-- 
2.45.2