Re: [dpdk-dev] [PATCH v2 4/6] baseband/acc100: add support for 4G CRC drop

["Chautru, Nicolas" <nicolas.chautru@intel.com>]

> -----Original Message-----
> From: Tom Rix <trix@redhat.com>
> Sent: Wednesday, September 1, 2021 7:20 AM
> To: Chautru, Nicolas <nicolas.chautru@intel.com>; dev@dpdk.org;
> gakhil@marvell.com
> Cc: thomas@monjalon.net; hemant.agrawal@nxp.com; Zhang, Mingshan
> <mingshan.zhang@intel.com>; Joshi, Arun <arun.joshi@intel.com>
> Subject: Re: [PATCH v2 4/6] baseband/acc100: add support for 4G CRC drop
> 
> 
> On 8/19/21 2:10 PM, Nicolas Chautru wrote:
> > This implements in PMD the option to drop the CB CRC after 4G decoding
> > to help transport block concatenation.
> >
> > Signed-off-by: Nicolas Chautru <nicolas.chautru@intel.com>
> > ---
> >   doc/guides/bbdevs/acc100.rst             |  1 +
> >   doc/guides/rel_notes/release_21_11.rst   |  4 ++++
> >   drivers/baseband/acc100/rte_acc100_pmd.c | 12 +++++++++---
> >   3 files changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/doc/guides/bbdevs/acc100.rst
> > b/doc/guides/bbdevs/acc100.rst index ff0fa4b..9fff6ab 100644
> > --- a/doc/guides/bbdevs/acc100.rst
> > +++ b/doc/guides/bbdevs/acc100.rst
> > @@ -58,6 +58,7 @@ ACC100 5G/4G FEC PMD supports the following BBDEV
> capabilities:
> >      - ``RTE_BBDEV_TURBO_NEG_LLR_1_BIT_IN`` :  set if negative LLR
> encoder i/p is supported
> >      - ``RTE_BBDEV_TURBO_POS_LLR_1_BIT_IN`` :  set if positive LLR encoder
> i/p is supported
> >      - ``RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP`` :  keep CRC24B bits
> > appended while decoding
> > +   - ``RTE_BBDEV_TURBO_DEC_CRC_24B_DROP`` : option to drop the code
> > + block CRC after decoding
> >      - ``RTE_BBDEV_TURBO_EARLY_TERMINATION`` :  set early termination
> feature
> >      - ``RTE_BBDEV_TURBO_DEC_SCATTER_GATHER`` :  supports scatter-
> gather for input/output data
> >      - ``RTE_BBDEV_TURBO_HALF_ITERATION_EVEN`` :  set half iteration
> > granularity diff --git a/doc/guides/rel_notes/release_21_11.rst
> > b/doc/guides/rel_notes/release_21_11.rst
> > index 8ca59b7..f7843bc 100644
> > --- a/doc/guides/rel_notes/release_21_11.rst
> > +++ b/doc/guides/rel_notes/release_21_11.rst
> > @@ -59,6 +59,10 @@ New Features
> >
> >     Added support for more comprehensive CRC options.
> >
> > +* **Updated the ACC100 bbdev PMD.**
> > +
> > +  Added support for more comprehensive CRC options.
> > +
> >   Removed Items
> >   -------------
> >
> > diff --git a/drivers/baseband/acc100/rte_acc100_pmd.c
> > b/drivers/baseband/acc100/rte_acc100_pmd.c
> > index 68ba523..891be81 100644
> > --- a/drivers/baseband/acc100/rte_acc100_pmd.c
> > +++ b/drivers/baseband/acc100/rte_acc100_pmd.c
> > @@ -980,6 +980,7 @@
> >
> 	RTE_BBDEV_TURBO_NEG_LLR_1_BIT_IN |
> >   					RTE_BBDEV_TURBO_MAP_DEC |
> >
> 	RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP |
> > +
> 	RTE_BBDEV_TURBO_DEC_CRC_24B_DROP |
> >
> 	RTE_BBDEV_TURBO_DEC_SCATTER_GATHER,
> >   				.max_llr_modulus = INT8_MAX,
> >   				.num_buffers_src =
> > @@ -1708,8 +1709,12 @@
> >   	}
> >
> >   	if ((op->turbo_dec.code_block_mode ==
> RTE_BBDEV_TRANSPORT_BLOCK)
> > -		&& !check_bit(op->turbo_dec.op_flags,
> > -		RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP))
> > +			&& !check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP))
> > +		crc24_overlap = 24;
> > +	if ((op->turbo_dec.code_block_mode == RTE_BBDEV_CODE_BLOCK)
> These two if-statements can be combined.

They could but really when I tried  that became arguably unreadable, I thought it was still better this way. 

> > +			&& check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_DEC_CRC_24B_DROP))
> >   		crc24_overlap = 24;
> >
> >   	/* Calculates circular buffer size.
> > @@ -1744,7 +1749,8 @@
> >
> >   	next_triplet = acc100_dma_fill_blk_type_out(
> >   			desc, h_output, *h_out_offset,
> > -			k >> 3, next_triplet,
> ACC100_DMA_BLKID_OUT_HARD);
> > +			(k - crc24_overlap)  >> 3, next_triplet,
> 
> crc24_overlap had been set before this patch in the above if-statement for
> crc_24b_keep.
> 
> so this looks like a bug.
> 
> If it is a bug, it should be separated out as its own patch.

Ok fair enough, will do. Thanks

> 
> Tom
> 
> > +			ACC100_DMA_BLKID_OUT_HARD);
> >   	if (unlikely(next_triplet < 0)) {
> >   		rte_bbdev_log(ERR,
> >   				"Mismatch between data to process and
> mbuf data length in
> > bbdev_op: %p",