AR #33710 - Endpoint Block Plus Wrapper v1.12 for PCI Express - Extended deassertions of trn_rnp_ok_n could result in completions being blocked inside the core
Endpoint Block Plus Wrapper v1.12 for PCI Express - Extended deassertions of trn_rnp_ok_n could result in completions being blocked inside the core
| AR# | 33710 |
| Topic | IP-SysIO-PCI Express Block Pls |
| Last Modified | 2009-10-23 00:00:00.0 |
| Status | Active |
Description
Keywords: BP, Non Posted, Ordering Rules
Known Issue: 1.12, v1.11, v1.10.1, v1.10, v1.9.4, v1.9.3, v1.9.2, v1.9.1, v1.9, v1.8, v1.7.1. v1.6, v1.5, v1.4, v1.3, v1.2, v1.1
By deasserting trn_rnp_ok_n, the user application instructs the wrapper to not send Non-Posted packets to the user. Posted and Completions packets should bypass the stalled Non-posted packets and be sent to the user application. A problem exists where if trn_rnp_ok_n is deasserted for such a period of time that the wrappers bypass packet queue fills with non-posted packets, the wrapper is no longer able to drain completion packets from the block if another non-posted packet is waiting in the integrated blocks receive buffer ahead of the completion packet.
Solution
This problem is rare and would only occur if trn_rnp_ok_n is deasserted for a long enough time that the block receives numerous non-posted packets. More than 8 non-posted packets would have to be received while trn_rnp_ok_n is deasserted for this problem to occur.Xilinx is currently investigating a work-around for this issue and plans to include a fix for this into the v1.13 core available in ISE Design Suite 11.4. If you believe you are experiencing this problem, please open a WebCase and refer to this Answer Record:
http://www.xilinx.com/support/clearexpress/websupport.htm
Revision History
10/26/2009 - Initial Release