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-rw-r--r--drivers/net/ethernet/intel/igb/igb_ptp.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 9f4d700e09df..29ced6b74d36 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -51,9 +51,15 @@
*
* The 40 bit 82580 SYSTIM overflows every
* 2^40 * 10^-9 / 60 = 18.3 minutes.
+ *
+ * SYSTIM is converted to real time using a timecounter. As
+ * timecounter_cyc2time() allows old timestamps, the timecounter
+ * needs to be updated at least once per half of the SYSTIM interval.
+ * Scheduling of delayed work is not very accurate, so we aim for 8
+ * minutes to be sure the actual interval is shorter than 9.16 minutes.
*/
-#define IGB_SYSTIM_OVERFLOW_PERIOD (HZ * 60 * 9)
+#define IGB_SYSTIM_OVERFLOW_PERIOD (HZ * 60 * 8)
#define IGB_PTP_TX_TIMEOUT (HZ * 15)
#define INCPERIOD_82576 BIT(E1000_TIMINCA_16NS_SHIFT)
#define INCVALUE_82576_MASK GENMASK(E1000_TIMINCA_16NS_SHIFT - 1, 0)