ERR004491
Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/2016
162
NXP Semiconductors
Description:
The PCI Express base specification states in section 3.5.2.1 “If REPLAY_NUM rolls over from
11b to 00b, the Transmitter signals the Physical Layer to retrain the Link, and waits for the
completion of retraining before proceeding with the replay.”
In the core, there are scenarios where the first TLP to be replayed might be replayed a fourth time
before the link is retrained. This happens because the replay buffer logic requests the link to retrain
at the same time that it begins a replay. If the link does not begin to retrain quickly enough, the first
TLP of the replay might be transmitted again prior to link retraining.
Conditions:
Scenario Setup:
1. Transmit a series of TLPs from the core.
2. Send a Nak DLLP for the first TLP to initiate a replay.
3. Wait for the replay to begin.
4. Send a Nak DLLP for the first TLP to again initiate a replay.
5. Repeat steps (3) and (4) two more times.
6. After sending the fourth NAK, in some circumstances the first replayed TLP might be seen
before the link begins to retrain.
Projected Impact:
A TLP is replayed before link retraining begins. However, the link recovers gracefully. After
retraining, the TLP will be replayed again as necessary, until successful transmission is achieved.
Workarounds:
None, the link recovers gracefully.
Proposed Solution:
No fix scheduled
Linux BSP Status:
Software workaround cannot be implemented to mask or workaround this SoC issue. This erratum
will result in impacted or reduced functionality as described above.
ERR004491
PCIe: 9000507633—TLP might be replayed an extra time before core
enters recovery
