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AR# 30054

LogiCORE RapidIO - CAR value read out is incorrect on certain offsets

Description

In SRIO v4.2 and v4.3, parameter settings in the customization GUI are not properly reflected in the CAR registers. The customization GUI will display the expected values according to your setting, but the actual value stored in the CAR/CSR might be incorrect. 

 

For example:  

 

1. In SRIO Customization GUI, you set Processing Element Features CAR (offset 0x10): to 0x40000009 for Memory, but the value read back from CAR is 0x00000009. 

 

2. In SRIO Customization GUI, you set Destination Operations CAR (offset 0x1C): to 0x0000F000 for simple target operation, but the value read back is 0x0000F3F8. 

 

3. Assembly Information CAR (offset 0xC) is also incorrect.

Solution

This issue does not change the functionality/behavior of the core, and will not impact any normal operations. However, the issue might be problematic at the system level, depending on what the host system is doing. If the host system reads the SRIO CAR and assumes that ATOMIC transactions are supported, but the FPGA user interface is not designed that way, that will be a problem. If the host system incorrectly assumes that the SRIO is Processing Element but it is actually a Memory Element, that might be a problem. The SRIO will be able to handle all of these transactions no matter what is said in the CAR, and pass them though the core, but if the User Interface is not designed to handle them, this could be an issue. 

 

This issue will be fixed in SRIO v4.4 Core, expected sometime after May 30, 2008. 

 

If you need a fix for this issue, please open a WebCase and ask for the IP-RapidIO expert: 

http://www.xilinx.com/support/clearexpress/websupport.htm
Please give the number of this Answer Record to the Technical Support Engineer.

AR# 30054
Date Created 02/21/2008
Last Updated 05/22/2014
Status Archive
Type General Article