Revision: 2.85

Specification Update

September 2012

32

Status:

A1, A2 NoFix

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40. TSYNC: Auxiliary Timestamp from SDP is Unreliable

Problem:

SDP inputs to the timestamp logic are not properly synchronized. As a result, both the

Auxiliary Timestamp Register values and the Auxiliary Timestamp Taken bits in TSAUXC

are sometimes loaded incorrectly.

Implication: The auxiliary timestamp feature should be considered unreliable.

Workaround: For applications that use the auxiliary timestamp feature to synchronize to an external

clock, it might be acceptable to drop some of the samples. For such applications, software

can filter out many of the incorrect timestamp values by comparing them to an

approximate expected timestamp and discarding unreasonable values.

In addition, the following method can be used to filter out incorrect values:

—

Connect the input signal to two SDP inputs for the same port.

—

Using the TSSDP register, assign one of the SDP inputs to AUX0 and the other SDP

input to AUX1.

—

When reading the TSAUXC register to check for new samples, check that both

AUTT0 and AUTT1 are set. Otherwise, discard the sample.

—

Read both the AUX0 and AUX1 timestamp values and compare the values. Discard

the values if they differ by more than the sampling uncertainty -- 8 ns if the SDP

inputs are balanced externally or slightly higher if the external trace lengths differ

significantly.

Using this method, along with a SW filter for expected values, almost all errors can be

filtered out with the remaining samples having a very high probability of being correct.

Status:

A1, A2 NoFix

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41. NC-SI: Get Link Status Command Might Cause Corruption of PHY Registers

Problem:

The firmware code that executes the NC-SI Get Link Status command does not acquire

the PHY semaphore bit when accessing PHY registers. Therefore, there could be

corruption of the PHY registers if the driver accesses PHY registers in parallel with the

firmware.

Implication: Corruption of the PHY registers could result in a link failure and/or a driver failure if NC-SI

Get Link Status command is used.

Workaround: None. See status.

Status:

A1, EEPROM/NVM Fix

Fixed in EEPROM version 2.1 or later.

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42. NC-SI: Get NC-SI Pass-through Statistics Response Format

Problem:

The NC-SI Specification, version 1.0.0a defines the Pass-through Tx Packets counter

contained in the Get NC-SI Pass-through Statistics Response Packet to be an 8-byte field.

The 82576 provides this counter as a 4-byte field.