New paragraph detailing typical VRAN usecase and mapping to bbdev API usage.
Signed-off-by: Nicolas Chautru <nicolas.chau...@intel.com> --- doc/guides/prog_guide/bbdev.rst | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/doc/guides/prog_guide/bbdev.rst b/doc/guides/prog_guide/bbdev.rst index 8bd7cba..f39b62f 100644 --- a/doc/guides/prog_guide/bbdev.rst +++ b/doc/guides/prog_guide/bbdev.rst @@ -1054,6 +1054,29 @@ capability RTE_BBDEV_LDPC_INTERNAL_HARQ_MEMORY_OUT_ENABLE is set then the HARQ is stored in memory internal to the device and not visible to BBDEV. +.. note:: + More explicitly for a typical usage of HARQ retransmission in a VRAN + application using a HW PMD, there will be 2 cases. + + For 1st transmission, only the HARQ output is enabled : + + - the harq_combined_output.offset is provided to a given address. ie. typically an integer index * 32K, where the index is tracked by the application based on code block index for a given UE and HARQ process. + + - the related operation flag would notably include RTE_BBDEV_LDPC_HQ_COMBINE_OUT_ENABLE and RTE_BBDEV_LDPC_HARQ_6BIT_COMPRESSION. + + - note that not explicit flush or reset of the memory is required. + + For 2nd transmission, an input is also required to benefit from HARQ combination gain: + + - the changes mentioned above are the same (note that rvIndex may be adjusted). + + - the operation flag would additionally include the LDPC_HQ_COMBINE_IN_ENABLE flag. + + - the harq_combined_input.offset must set to the address of the related code block (ie. same as the harq_combine_output index above for the same code block, HARQ process, UE). + + - the harq_combined_input.length must be set to the length which was provided back in the related harq_combined_output.length when it has processed and dequeued (previous HARQ iteration). + + The output mbuf data structures are expected to be allocated by the application with enough room for the output data. -- 1.8.3.1
