HMC Controller Does Not Properly Process HMC Packets Received Immediately Following a Short Retry Sequence

If the Hybrid Memory Cube (HMC) Controller IP core receives a packet in the first few FLITs that follow a short incoming error recovery sequence (20 consecutive IRTRY packets), the IP core might not process all of the packet fields properly.

The impact depends on the type of the packet and the fields that are processed incorrectly. For example, if the IP core ignores a SEQ field, the following incoming packet appears to the IP core to have an incorrect SEQ field. In that case, the IP core marks the new incoming packet as errored.

This issue affects all full-width variations of the Hybrid Memory Cube Controller IP core.

Refer also to the special case HMC Controller IP Core Might Not Acknowledge HMC Packets Received Immediately Following a Retry Sequence.

To avoid this issue, configure the Hybrid Memory Cube to send at least 50 IRTRY packets in a retry sequence. To configure this property, set the Init retry packet transmit number field of the HMC device Link Retry register to the value of 13 or higher.

Note that this workaround also works around the issue in the special case HMC Controller IP Core Might Not Acknowledge HMC Packets Received Immediately Following a Retry Sequence. The workaround for HMC Controller IP Core Might Not Acknowledge HMC Packets Received Immediately Following a Retry Sequence is not sufficient to cover all cases of this erratum.

This issue will be fixed in a future version of the HMC Controller IP core.