From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next 09/15] e1000e: 82574/82583 TimeSync errata for SYSTIM read Date: Tue, 27 May 2014 02:12:25 -0700 Message-ID: <1401181951-31358-10-git-send-email-jeffrey.t.kirsher@intel.com> References: <1401181951-31358-1-git-send-email-jeffrey.t.kirsher@intel.com> Cc: Todd Fujinaka , netdev@vger.kernel.org, gospo@redhat.com, sassmann@redhat.com, Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga02.intel.com ([134.134.136.20]:17019 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752166AbaE0JMn (ORCPT ); Tue, 27 May 2014 05:12:43 -0400 In-Reply-To: <1401181951-31358-1-git-send-email-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Todd Fujinaka Due to a synchronization error, the value read from SYSTIML/SYSTIMH might be incorrect. Signed-off-by: Todd Fujinaka Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/e1000e/e1000.h | 2 ++ drivers/net/ethernet/intel/e1000e/netdev.c | 27 ++++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/e1000e/e1000.h b/drivers/net/ethernet/intel/e1000e/e1000.h index e27e609..63bde99 100644 --- a/drivers/net/ethernet/intel/e1000e/e1000.h +++ b/drivers/net/ethernet/intel/e1000e/e1000.h @@ -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) diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c index 6084e6b..95cf482 100644 --- a/drivers/net/ethernet/intel/e1000e/netdev.c +++ b/drivers/net/ethernet/intel/e1000e/netdev.c @@ -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; } -- 1.9.3