Details:

RAT logic inside R5SS uses rbytecnt and wbytecnt to determine if read or write access crosses the region boundaries configured by SW. The rbytecnt and wbytecnt values sent to the RAT are computed in the R5SS, but the equations used are incorrect.

This results in the RAT not detecting or erroneously detecting region boundary crossings.

Workaround(s):

Because the Cortex-R5 AXI main interface transactions do not cross a 32 byte boundary, there are no issues with region boundaries equal to or greater than 32 bytes. The issue only occurs when the region boundary is less than 32 bytes. Therefore software can not set region boundaries that are less than 32 bytes.