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e1000e: 82574/82583 TimeSync errata for SYSTIM read

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Due to a synchronization error, the value read from SYSTIML/SYSTIMH
might be incorrect.

Signed-off-by: Todd Fujinaka <todd.fujinaka@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Todd Fujinaka 2014-05-03 06:41:37 +00:00 committed by Jeff Kirsher
parent b3e5bf1ff3
commit 5e7ff97004
2 changed files with 28 additions and 1 deletions
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2
drivers/net/ethernet/intel/e1000e/e1000.h
View file

@ -391,6 +391,8 @@ s32 e1000e_get_base_timinca(struct e1000_adapter *adapter, u32 *timinca);
* 25MHz 46-bit 2^46 / 10^9 / 3600 = 19.55 hours
*/
#define E1000_SYSTIM_OVERFLOW_PERIOD (HZ * 60 * 60 * 4)
#define E1000_MAX_82574_SYSTIM_REREADS 50
#define E1000_82574_SYSTIM_EPSILON (1ULL << 35ULL)
/* hardware capability, feature, and workaround flags */
#define FLAG_HAS_AMT (1 << 0)

27
drivers/net/ethernet/intel/e1000e/netdev.c
View file

@ -4099,12 +4099,37 @@ static cycle_t e1000e_cyclecounter_read(const struct cyclecounter *cc)
struct e1000_adapter *adapter = container_of(cc, struct e1000_adapter,
cc);
struct e1000_hw *hw = &adapter->hw;
cycle_t systim;
cycle_t systim, systim_next;
/* latch SYSTIMH on read of SYSTIML */
systim = (cycle_t)er32(SYSTIML);
systim |= (cycle_t)er32(SYSTIMH) << 32;
if ((hw->mac.type == e1000_82574) || (hw->mac.type == e1000_82583)) {
u64 incvalue, time_delta, rem, temp;
int i;
/* errata for 82574/82583 possible bad bits read from SYSTIMH/L
* check to see that the time is incrementing at a reasonable
* rate and is a multiple of incvalue
*/
incvalue = er32(TIMINCA) & E1000_TIMINCA_INCVALUE_MASK;
for (i = 0; i < E1000_MAX_82574_SYSTIM_REREADS; i++) {
/* latch SYSTIMH on read of SYSTIML */
systim_next = (cycle_t)er32(SYSTIML);
systim_next |= (cycle_t)er32(SYSTIMH) << 32;
time_delta = systim_next - systim;
temp = time_delta;
rem = do_div(temp, incvalue);
systim = systim_next;
if ((time_delta < E1000_82574_SYSTIM_EPSILON) &&
(rem == 0))
break;
}
}
return systim;
}