diff options
| author | Miroslav Lichvar <mlichvar@redhat.com> | 2018-10-26 19:13:00 +0200 |
|---|---|---|
| committer | Jeff Kirsher <jeffrey.t.kirsher@intel.com> | 2018-11-06 12:54:27 -0800 |
| commit | 4c9b658eeaefedd402a59e858d8ac3bfdf6153e3 (patch) | |
| tree | 1131ab8b79b517f4554c4a3141a58ca96c6adeef | |
| parent | d944b46992f8e99b6bdc721e44b02e5ca294fa2b (diff) | |
| download | linux-4c9b658eeaefedd402a59e858d8ac3bfdf6153e3.tar.bz2 | |
igb: shorten maximum PHC timecounter update interval
The timecounter needs to be updated at least once per ~550 seconds in
order to avoid a 40-bit SYSTIM timestamp to be misinterpreted as an old
timestamp.
Since commit 500462a9de65 ("timers: Switch to a non-cascading wheel"),
scheduling of delayed work seems to be less accurate and a requested
delay of 540 seconds may actually be longer than 550 seconds. Also, the
PHC may be adjusted to run up to 6% faster than real time and the system
clock up to 10% slower. Shorten the delay to 360 seconds to be sure the
timecounter is updated in time.
This fixes an issue with HW timestamps on 82580/I350/I354 being off by
~1100 seconds for few seconds every ~9 minutes.
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
| -rw-r--r-- | drivers/net/ethernet/intel/igb/igb_ptp.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c index 29ced6b74d36..2b95dc9c7a6a 100644 --- a/drivers/net/ethernet/intel/igb/igb_ptp.c +++ b/drivers/net/ethernet/intel/igb/igb_ptp.c @@ -53,13 +53,15 @@ * 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. + * 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, and also the NIC + * clock can be adjusted to run up to 6% faster and the system clock + * up to 10% slower, so we aim for 6 minutes to be sure the actual + * interval in the NIC time is shorter than 9.16 minutes. */ -#define IGB_SYSTIM_OVERFLOW_PERIOD (HZ * 60 * 8) +#define IGB_SYSTIM_OVERFLOW_PERIOD (HZ * 60 * 6) #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) |