From: Jacob Keller Date: Sat, 16 Jun 2012 23:29:00 +0000 (+0000) Subject: ixgbe: Fix PHC loophole allowing misconfiguration of increment register X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=b6138ed60457ef1e9150692f6790eb4a2a696308;p=deliverable%2Flinux.git ixgbe: Fix PHC loophole allowing misconfiguration of increment register This patch fixes a potential hole when configuring the cycle counter used to generate the nanosecond time clock. This clock is based off of the SYSTIME registers along with the TIMINCA registers. The TIMINCA register determines the increment to be added to the SYSTIME registers every DMA clock tick. This register needs to be reconfigured whenever the link-speed changes. However, the value calculated stays the same when link is down and when link is up. Misconfiguration can occur if the link status changes due to a reset, which causes the TIMINCA register to be reset. This reset puts the device in an unstable state where the SYSTIME registers stop incrementing and the PTP protocol does not function. The solution is to double check the TIMINCA value and always reset the value if the register is zero. This prevents a misconfiguration bug that halts the PHC. Signed-off-by: Jacob Keller Acked-by: Don Skidmore Tested-by: Phil Schmitt Signed-off-by: Jeff Kirsher Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c index ddc6a4d19302..dcebd128becf 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c @@ -708,6 +708,7 @@ void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter) { struct ixgbe_hw *hw = &adapter->hw; u32 incval = 0; + u32 timinca = 0; u32 shift = 0; u32 cycle_speed; unsigned long flags; @@ -730,8 +731,16 @@ void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter) break; } - /* Bail if the cycle speed didn't change */ - if (adapter->cycle_speed == cycle_speed) + /* + * grab the current TIMINCA value from the register so that it can be + * double checked. If the register value has been cleared, it must be + * reset to the correct value for generating a cyclecounter. If + * TIMINCA is zero, the SYSTIME registers do not increment at all. + */ + timinca = IXGBE_READ_REG(hw, IXGBE_TIMINCA); + + /* Bail if the cycle speed didn't change and TIMINCA is non-zero */ + if (adapter->cycle_speed == cycle_speed && timinca) return; /* disable the SDP clock out */