ERR003753
Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/2016
NXP Semiconductors
145
Description:
The completion timeout mechanism defined in Section 2.8 of PCIe Base Specification version 2.1
describes a method to allow a requester to recover from a scenario where it does not receive all
completions to a non-posted request. In the AXI or AHB bridge module, this triggers an error
response to the original request on the slave interface.
There is a separate completion timeout interface that passes information about the request that has
been timed out from the PCIe Core to the AXI or AHB Bridge. The Bridge cannot process valid
completions and completion timeouts in parallel and so, if a completion timeout is received at the
same time as a valid completion is passed into the bridge, it must be stored and processed later.
There is only a single storage element available for a completion timeout in the bridge. If a second
completion timeout is passed into the bridge before it processes the first, the second timeout will
overwrite the first completion timeout in the storage element. This results in the information
associated with the first timeout being lost and no response is returned on the AHB or AXI slave
interface for the original request.
Following is an example scenario for this erratum:
1. Issue a continuous stream of outbound MemRd requests targeting the AXI or AHB Slave
interface.
2. Correctly return completions back to back for all but two of these requests.
3. Wait for the timeout mechanism to trigger for the two requests that do not receive completions.
Projected Impact:
If all the steps of the example scenario, given in the Description section, are performed, then there
will be no response on the AHB or AXI slave interface for the first non-posted request that triggers
a completion timeout. The second request to trigger a completion timeout will correctly receive an
ERROR response on the AXI or AHB slave interface.
Workarounds:
None
Proposed Solution:
No fix scheduled
Linux BSP Status:
No software workaround can be implemented to mask or workaround this erratum. This erratum
will result in impacted or reduced functionality as described above.
ERR003753
PCIe: 9000405932—AXI/AHB Bridge Slave does not return a response
to an outbound non-posted request
