Revision: 2.85

September 2012

Specification Update

25

Status:

A1, A2 NoFix

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17. SMBus: Unread Packets Received On One Port May Cause Loss of Ability To Receive on Other Port

Problem:

The device’s two ports share memory. When packets are received by one of the ports and

not read, they are stored in the shared memory. When this memory fills up, no more

packets may be received.

Implication: The MC should be aware of the above behavior.

Workaround: 1. Make use of a SMBus alert timeout mechanism.

2. Read data and/or momentarily disable receives by the other port.

Status:

A1, A2 NoFix

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18. JTAG: Instruction Register Functionality Doesn't Meet IEEE Std 1149-1-2001

Problem:

If UPDATE_IR directly follows CAPTURE_IR, the active instruction is DEVID. This is not as

specified by the INSTRUCTION_CAPTURE attribute.

Implication: The value from CAPTURE_IR cannot be relied upon.

Workaround: Shift in an instruction; do not rely on the value from CAPTURE_IR.

Status:

A1, A2 NoFix

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19. LED Stays On When SerDes Is Powered Down

Problem:

The LED may remain on in D3 power state when SerDes power down is enabled (EEPROM

word 0xf, bit 1; register CTRL_EXT 0x0018, bit 18). If a link is established when the

device enters D3 power state and the LED mode is programmed to reflect LINK

indication, the LED remains on even though the SerDes interface powers down.

Implication: LED incorrectly reflects link is up when there is no link (as SerDes is powered off).

Workaround: When using the Intel Fiber adapters based on the 82576, the driver should disable optics

Status:

A1, A2 NoFix

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20. PCIe Elastic Buffer Noise Immunity Is Not Optimized

Problem:

The PCIe elastic buffer is used to synchronize between the clock generated by the clock

recovery circuit and the internal clock. During electrical idle, in the absence of an input

signal, the clock recovery circuit can be disturbed by noise and move the elastic buffer fill

level away from the optimum value.

In the EEPROM, control bits were implemented to maintain stability during electrical idle.

In the default EEPROM image provided, these bits were not set correctly.

Implication: In cases of increased noise levels during Electrical Idle, elastic buffer instability may

cause a link training failure when exiting from L0s or (in rare instances) L1 state.