Details:

The C71x Streaming Engine's (SE) pipeline for returning formatted data and return report internal error information is always monitoring the tags for the data that it is working on. When an error is detected for a line of data used to format data back to the CPU, all fetching side execution for queuing up commands to go to UMC, uTLB, and the formatting pipeline back to CPU is halted.

In general operation, the only tags monitored for errors are the ones being used for the current command. For transposed mode, this is all tags touched by the current array column. A gap in suppressing internal tag monitoring causes the formatting pipeline to monitor tags that it is not currently working on while creating zero vectors for the LEZR feature. If the SE's fetching side encounters and records an error for a future column, the formatting side may notice it and halt the fetching side before the command for that column has been committed for formatting.

Errors are only reported back to the CPU for commands that are internally committed for formatting, thus halting internal execution before committing the column results in no error being reported to the CPU. Because the SE has halted fetching operations without reporting an error, the CPU proceeds to hang, waiting for either return data or an error from the SE, until an unrelated external event or interrupt occurs.

Workaround(s):

The only 100% workaround is to not use stream templates with both LEZR and transposed mode enabled.