RE: [PATCH v9 09/14] baseband/acc: add LTE processing functions

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

Hi Maxime, 

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Monday, October 10, 2022 2:48 AM
> To: Chautru, Nicolas <nicolas.chautru@intel.com>; dev@dpdk.org;
> gakhil@marvell.com
> Cc: trix@redhat.com; mdr@ashroe.eu; Richardson, Bruce
> <bruce.richardson@intel.com>; hemant.agrawal@nxp.com;
> david.marchand@redhat.com; stephen@networkplumber.org; Vargas,
> Hernan <hernan.vargas@intel.com>
> Subject: Re: [PATCH v9 09/14] baseband/acc: add LTE processing functions
> 
> 
> 
> On 10/7/22 23:38, Nicolas Chautru wrote:
> > From: Nic Chautru <nicolas.chautru@intel.com>
> >
> > Added functions and capability for 4G FEC
> >
> > Signed-off-by: Nic Chautru <nicolas.chautru@intel.com>
> > ---
> >   drivers/baseband/acc/rte_acc200_pmd.c | 851
> +++++++++++++++++++++++++-
> >   1 file changed, 846 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/baseband/acc/rte_acc200_pmd.c
> > b/drivers/baseband/acc/rte_acc200_pmd.c
> > index 0f018b19ac..058e38c3ec 100644
> > --- a/drivers/baseband/acc/rte_acc200_pmd.c
> > +++ b/drivers/baseband/acc/rte_acc200_pmd.c
> > @@ -649,6 +649,46 @@ acc200_dev_info_get(struct rte_bbdev *dev,
> >   	struct acc_device *d = dev->data->dev_private;
> >   	int i;
> >   	static const struct rte_bbdev_op_cap bbdev_capabilities[] = {
> > +		{
> > +			.type = RTE_BBDEV_OP_TURBO_DEC,
> > +			.cap.turbo_dec = {
> > +				.capability_flags =
> > +
> 	RTE_BBDEV_TURBO_SUBBLOCK_DEINTERLEAVE |
> > +					RTE_BBDEV_TURBO_CRC_TYPE_24B
> |
> > +					RTE_BBDEV_TURBO_EQUALIZER |
> > +
> 	RTE_BBDEV_TURBO_SOFT_OUT_SATURATE |
> > +
> 	RTE_BBDEV_TURBO_HALF_ITERATION_EVEN |
> > +
> 	RTE_BBDEV_TURBO_CONTINUE_CRC_MATCH |
> > +					RTE_BBDEV_TURBO_SOFT_OUTPUT
> |
> > +
> 	RTE_BBDEV_TURBO_EARLY_TERMINATION |
> > +
> 	RTE_BBDEV_TURBO_NEG_LLR_1_BIT_IN |
> > +
> 	RTE_BBDEV_TURBO_NEG_LLR_1_BIT_SOFT_OUT |
> > +					RTE_BBDEV_TURBO_MAP_DEC |
> > +
> 	RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP |
> > +
> 	RTE_BBDEV_TURBO_DEC_SCATTER_GATHER,
> > +				.max_llr_modulus = INT8_MAX,
> > +				.num_buffers_src =
> > +
> 	RTE_BBDEV_TURBO_MAX_CODE_BLOCKS,
> > +				.num_buffers_hard_out =
> > +
> 	RTE_BBDEV_TURBO_MAX_CODE_BLOCKS,
> > +				.num_buffers_soft_out =
> > +
> 	RTE_BBDEV_TURBO_MAX_CODE_BLOCKS,
> > +			}
> > +		},
> > +		{
> > +			.type = RTE_BBDEV_OP_TURBO_ENC,
> > +			.cap.turbo_enc = {
> > +				.capability_flags =
> > +
> 	RTE_BBDEV_TURBO_CRC_24B_ATTACH |
> > +
> 	RTE_BBDEV_TURBO_RV_INDEX_BYPASS |
> > +					RTE_BBDEV_TURBO_RATE_MATCH |
> > +
> 	RTE_BBDEV_TURBO_ENC_SCATTER_GATHER,
> > +				.num_buffers_src =
> > +
> 	RTE_BBDEV_TURBO_MAX_CODE_BLOCKS,
> > +				.num_buffers_dst =
> > +
> 	RTE_BBDEV_TURBO_MAX_CODE_BLOCKS,
> > +			}
> > +		},
> >   		{
> >   			.type   = RTE_BBDEV_OP_LDPC_ENC,
> >   			.cap.ldpc_enc = {
> > @@ -700,15 +740,17 @@ acc200_dev_info_get(struct rte_bbdev *dev,
> >
> >   	/* Exposed number of queues. */
> >   	dev_info->num_queues[RTE_BBDEV_OP_NONE] = 0;
> > -	dev_info->num_queues[RTE_BBDEV_OP_TURBO_DEC] = 0;
> > -	dev_info->num_queues[RTE_BBDEV_OP_TURBO_ENC] = 0;
> > +	dev_info->num_queues[RTE_BBDEV_OP_TURBO_DEC] = d-
> >acc_conf.q_ul_4g.num_aqs_per_groups *
> > +			d->acc_conf.q_ul_4g.num_qgroups;
> > +	dev_info->num_queues[RTE_BBDEV_OP_TURBO_ENC] = d-
> >acc_conf.q_dl_4g.num_aqs_per_groups *
> > +			d->acc_conf.q_dl_4g.num_qgroups;
> >   	dev_info->num_queues[RTE_BBDEV_OP_LDPC_DEC] = d-
> >acc_conf.q_ul_5g.num_aqs_per_groups *
> >   			d->acc_conf.q_ul_5g.num_qgroups;
> >   	dev_info->num_queues[RTE_BBDEV_OP_LDPC_ENC] = d-
> >acc_conf.q_dl_5g.num_aqs_per_groups *
> >   			d->acc_conf.q_dl_5g.num_qgroups;
> >   	dev_info->num_queues[RTE_BBDEV_OP_FFT] = 0;
> > -	dev_info->queue_priority[RTE_BBDEV_OP_TURBO_DEC] = 0;
> > -	dev_info->queue_priority[RTE_BBDEV_OP_TURBO_ENC] = 0;
> > +	dev_info->queue_priority[RTE_BBDEV_OP_TURBO_DEC] = d-
> >acc_conf.q_ul_4g.num_qgroups;
> > +	dev_info->queue_priority[RTE_BBDEV_OP_TURBO_ENC] =
> > +d->acc_conf.q_dl_4g.num_qgroups;
> >   	dev_info->queue_priority[RTE_BBDEV_OP_LDPC_DEC] = d-
> >acc_conf.q_ul_5g.num_qgroups;
> >   	dev_info->queue_priority[RTE_BBDEV_OP_LDPC_ENC] = d-
> >acc_conf.q_dl_5g.num_qgroups;
> >   	dev_info->queue_priority[RTE_BBDEV_OP_FFT] = 0; @@ -753,6
> +795,70
> > @@ static struct rte_pci_id pci_id_acc200_vf_map[] = {
> >   	{.device_id = 0},
> >   };
> >
> > +/* Fill in a frame control word for turbo decoding. */ static inline
> > +void acc200_fcw_td_fill(const struct rte_bbdev_dec_op *op, struct
> > +acc_fcw_td *fcw) {
> > +	fcw->fcw_ver = 1;
> > +	fcw->num_maps = ACC_FCW_TD_AUTOMAP;
> > +	fcw->bypass_sb_deint = !check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_SUBBLOCK_DEINTERLEAVE);
> > +	if (op->turbo_dec.code_block_mode ==
> RTE_BBDEV_TRANSPORT_BLOCK) {
> > +		/* FIXME for TB block */
> > +		fcw->k_pos = op->turbo_dec.tb_params.k_pos;
> > +		fcw->k_neg = op->turbo_dec.tb_params.k_neg;
> > +	} else {
> > +		fcw->k_pos = op->turbo_dec.cb_params.k;
> > +		fcw->k_neg = op->turbo_dec.cb_params.k;
> > +	}
> > +	fcw->c = 1;
> > +	fcw->c_neg = 1;
> > +	if (check_bit(op->turbo_dec.op_flags,
> RTE_BBDEV_TURBO_SOFT_OUTPUT)) {
> > +		fcw->soft_output_en = 1;
> > +		fcw->sw_soft_out_dis = 0;
> > +		fcw->sw_et_cont = check_bit(op->turbo_dec.op_flags,
> > +
> 	RTE_BBDEV_TURBO_CONTINUE_CRC_MATCH);
> > +		fcw->sw_soft_out_saturation = check_bit(op-
> >turbo_dec.op_flags,
> > +
> 	RTE_BBDEV_TURBO_SOFT_OUT_SATURATE);
> > +		if (check_bit(op->turbo_dec.op_flags,
> > +				RTE_BBDEV_TURBO_EQUALIZER)) {
> > +			fcw->bypass_teq = 0;
> > +			fcw->ea = op->turbo_dec.cb_params.e;
> > +			fcw->eb = op->turbo_dec.cb_params.e;
> > +			if (op->turbo_dec.rv_index == 0)
> > +				fcw->k0_start_col = ACC_FCW_TD_RVIDX_0;
> > +			else if (op->turbo_dec.rv_index == 1)
> > +				fcw->k0_start_col = ACC_FCW_TD_RVIDX_1;
> > +			else if (op->turbo_dec.rv_index == 2)
> > +				fcw->k0_start_col = ACC_FCW_TD_RVIDX_2;
> > +			else
> > +				fcw->k0_start_col = ACC_FCW_TD_RVIDX_3;
> > +		} else {
> > +			fcw->bypass_teq = 1;
> > +			fcw->eb = 64; /* avoid undefined value */
> > +		}
> > +	} else {
> > +		fcw->soft_output_en = 0;
> > +		fcw->sw_soft_out_dis = 1;
> > +		fcw->bypass_teq = 0;
> > +	}
> > +
> > +	fcw->code_block_mode = 1; /* FIXME */
> > +	fcw->turbo_crc_type = check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_CRC_TYPE_24B);
> > +
> > +	fcw->ext_td_cold_reg_en = 1;
> > +	fcw->raw_decoder_input_on = 0;
> > +	fcw->max_iter = RTE_MAX((uint8_t) op->turbo_dec.iter_max, 2);
> > +	fcw->min_iter = 2;
> > +	fcw->half_iter_on = !check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_HALF_ITERATION_EVEN);
> > +
> > +	fcw->early_stop_en = check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_EARLY_TERMINATION) & !fcw-
> >soft_output_en;
> > +	fcw->ext_scale = 0xF;
> > +}
> > +
> >   /* Fill in a frame control word for LDPC decoding. */
> >   static inline void
> >   acc200_fcw_ld_fill(struct rte_bbdev_dec_op *op, struct acc_fcw_ld
> > *fcw, @@ -876,7 +982,206 @@ acc200_fcw_ld_fill(struct
> rte_bbdev_dec_op *op, struct acc_fcw_ld *fcw,
> >   }
> >
> >   static inline int
> > -acc200_dma_desc_ld_fill(struct rte_bbdev_dec_op *op, struct
> > acc_dma_req_desc *desc,
> > +acc200_dma_desc_te_fill(struct rte_bbdev_enc_op *op,
> > +		struct acc_dma_req_desc *desc, struct rte_mbuf **input,
> > +		struct rte_mbuf *output, uint32_t *in_offset,
> > +		uint32_t *out_offset, uint32_t *out_length,
> > +		uint32_t *mbuf_total_left, uint32_t *seg_total_left, uint8_t
> r) {
> > +	int next_triplet = 1; /* FCW already done. */
> > +	uint32_t e, ea, eb, length;
> > +	uint16_t k, k_neg, k_pos;
> > +	uint8_t cab, c_neg;
> > +
> > +	desc->word0 = ACC_DMA_DESC_TYPE;
> > +	desc->word1 = 0; /**< Timestamp could be disabled. */
> > +	desc->word2 = 0;
> > +	desc->word3 = 0;
> > +	desc->numCBs = 1;
> > +
> > +	if (op->turbo_enc.code_block_mode ==
> RTE_BBDEV_TRANSPORT_BLOCK) {
> > +		ea = op->turbo_enc.tb_params.ea;
> > +		eb = op->turbo_enc.tb_params.eb;
> > +		cab = op->turbo_enc.tb_params.cab;
> > +		k_neg = op->turbo_enc.tb_params.k_neg;
> > +		k_pos = op->turbo_enc.tb_params.k_pos;
> > +		c_neg = op->turbo_enc.tb_params.c_neg;
> > +		e = (r < cab) ? ea : eb;
> > +		k = (r < c_neg) ? k_neg : k_pos;
> > +	} else {
> > +		e = op->turbo_enc.cb_params.e;
> > +		k = op->turbo_enc.cb_params.k;
> > +	}
> > +
> > +	if (check_bit(op->turbo_enc.op_flags,
> RTE_BBDEV_TURBO_CRC_24B_ATTACH))
> > +		length = (k - 24) >> 3;
> > +	else
> > +		length = k >> 3;
> > +
> > +	if (unlikely((*mbuf_total_left == 0) || (*mbuf_total_left < length))) {
> > +		rte_bbdev_log(ERR,
> > +				"Mismatch between mbuf length and
> included CB sizes: mbuf len %u, cb len %u",
> > +				*mbuf_total_left, length);
> > +		return -1;
> > +	}
> > +
> > +	next_triplet = acc_dma_fill_blk_type_in(desc, input, in_offset,
> > +			length, seg_total_left, next_triplet,
> > +			check_bit(op->turbo_enc.op_flags,
> RTE_BBDEV_TURBO_ENC_SCATTER_GATHER));
> > +	if (unlikely(next_triplet < 0)) {
> > +		rte_bbdev_log(ERR,
> > +				"Mismatch between data to process and
> mbuf data length in bbdev_op: %p",
> > +				op);
> > +		return -1;
> > +	}
> > +	desc->data_ptrs[next_triplet - 1].last = 1;
> > +	desc->m2dlen = next_triplet;
> > +	*mbuf_total_left -= length;
> > +
> > +	/* Set output length. */
> > +	if (check_bit(op->turbo_enc.op_flags,
> RTE_BBDEV_TURBO_RATE_MATCH))
> > +		/* Integer round up division by 8. */
> > +		*out_length = (e + 7) >> 3;
> > +	else
> > +		*out_length = (k >> 3) * 3 + 2;
> > +
> > +	next_triplet = acc_dma_fill_blk_type(desc, output, *out_offset,
> > +			*out_length, next_triplet,
> ACC_DMA_BLKID_OUT_ENC);
> > +	if (unlikely(next_triplet < 0)) {
> > +		rte_bbdev_log(ERR,
> > +				"Mismatch between data to process and
> mbuf data length in bbdev_op: %p",
> > +				op);
> > +		return -1;
> > +	}
> > +	op->turbo_enc.output.length += *out_length;
> > +	*out_offset += *out_length;
> > +	desc->data_ptrs[next_triplet - 1].last = 1;
> > +	desc->d2mlen = next_triplet - desc->m2dlen;
> > +
> > +	desc->op_addr = op;
> > +
> > +	return 0;
> > +}
> > +
> > +static inline int
> > +acc200_dma_desc_td_fill(struct rte_bbdev_dec_op *op,
> > +		struct acc_dma_req_desc *desc, struct rte_mbuf **input,
> > +		struct rte_mbuf *h_output, struct rte_mbuf *s_output,
> > +		uint32_t *in_offset, uint32_t *h_out_offset,
> > +		uint32_t *s_out_offset, uint32_t *h_out_length,
> > +		uint32_t *s_out_length, uint32_t *mbuf_total_left,
> > +		uint32_t *seg_total_left, uint8_t r) {
> > +	int next_triplet = 1; /* FCW already done. */
> > +	uint16_t k;
> > +	uint16_t crc24_overlap = 0;
> > +	uint32_t e, kw;
> > +
> > +	desc->word0 = ACC_DMA_DESC_TYPE;
> > +	desc->word1 = 0; /**< Timestamp could be disabled. */
> > +	desc->word2 = 0;
> > +	desc->word3 = 0;
> > +	desc->numCBs = 1;
> > +
> > +	if (op->turbo_dec.code_block_mode ==
> RTE_BBDEV_TRANSPORT_BLOCK) {
> > +		k = (r < op->turbo_dec.tb_params.c_neg)
> > +			? op->turbo_dec.tb_params.k_neg
> > +			: op->turbo_dec.tb_params.k_pos;
> > +		e = (r < op->turbo_dec.tb_params.cab)
> > +			? op->turbo_dec.tb_params.ea
> > +			: op->turbo_dec.tb_params.eb;
> > +	} else {
> > +		k = op->turbo_dec.cb_params.k;
> > +		e = op->turbo_dec.cb_params.e;
> > +	}
> > +
> > +	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))
> > +		crc24_overlap = 24;
> > +
> > +	/* Calculates circular buffer size.
> > +	 * According to 3gpp 36.212 section 5.1.4.2
> > +	 *   Kw = 3 * Kpi,
> > +	 * where:
> > +	 *   Kpi = nCol * nRow
> > +	 * where nCol is 32 and nRow can be calculated from:
> > +	 *   D =< nCol * nRow
> > +	 * where D is the size of each output from turbo encoder block (k +
> 4).
> > +	 */
> > +	kw = RTE_ALIGN_CEIL(k + 4, 32) * 3;
> > +
> > +	if (unlikely((*mbuf_total_left == 0) || (*mbuf_total_left < kw))) {
> > +		rte_bbdev_log(ERR,
> > +				"Mismatch between mbuf length and
> included CB sizes: mbuf len %u, cb len %u",
> > +				*mbuf_total_left, kw);
> > +		return -1;
> > +	}
> > +
> > +	next_triplet = acc_dma_fill_blk_type_in(desc, input, in_offset, kw,
> > +			seg_total_left, next_triplet,
> > +			check_bit(op->turbo_dec.op_flags,
> > +			RTE_BBDEV_TURBO_DEC_SCATTER_GATHER));
> > +	if (unlikely(next_triplet < 0)) {
> > +		rte_bbdev_log(ERR,
> > +				"Mismatch between data to process and
> mbuf data length in bbdev_op: %p",
> > +				op);
> > +		return -1;
> > +	}
> > +	desc->data_ptrs[next_triplet - 1].last = 1;
> > +	desc->m2dlen = next_triplet;
> > +	*mbuf_total_left -= kw;
> > +	*h_out_length = ((k - crc24_overlap) >> 3);
> > +	next_triplet = acc_dma_fill_blk_type(
> > +			desc, h_output, *h_out_offset,
> > +			*h_out_length, next_triplet,
> ACC_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",
> > +				op);
> > +		return -1;
> > +	}
> > +
> > +	op->turbo_dec.hard_output.length += *h_out_length;
> > +	*h_out_offset += *h_out_length;
> > +
> > +	/* Soft output. */
> > +	if (check_bit(op->turbo_dec.op_flags,
> RTE_BBDEV_TURBO_SOFT_OUTPUT)) {
> > +		if (op->turbo_dec.soft_output.data == 0) {
> > +			rte_bbdev_log(ERR, "Soft output is not defined");
> > +			return -1;
> > +		}
> > +		if (check_bit(op->turbo_dec.op_flags,
> > +				RTE_BBDEV_TURBO_EQUALIZER))
> > +			*s_out_length = e;
> > +		else
> > +			*s_out_length = (k * 3) + 12;
> > +
> > +		next_triplet = acc_dma_fill_blk_type(desc, s_output,
> > +				*s_out_offset, *s_out_length, next_triplet,
> > +				ACC_DMA_BLKID_OUT_SOFT);
> > +		if (unlikely(next_triplet < 0)) {
> > +			rte_bbdev_log(ERR,
> > +					"Mismatch between data to process
> and mbuf data length in bbdev_op: %p",
> > +					op);
> > +			return -1;
> > +		}
> > +
> > +		op->turbo_dec.soft_output.length += *s_out_length;
> > +		*s_out_offset += *s_out_length;
> > +	}
> > +
> > +	desc->data_ptrs[next_triplet - 1].last = 1;
> > +	desc->d2mlen = next_triplet - desc->m2dlen;
> > +
> > +	desc->op_addr = op;
> > +
> > +	return 0;
> > +}
> > +
> > +static inline int
> > +acc200_dma_desc_ld_fill(struct rte_bbdev_dec_op *op,
> > +		struct acc_dma_req_desc *desc,
> >   		struct rte_mbuf **input, struct rte_mbuf *h_output,
> >   		uint32_t *in_offset, uint32_t *h_out_offset,
> >   		uint32_t *h_out_length, uint32_t *mbuf_total_left, @@ -
> 1034,6
> > +1339,49 @@ acc200_dma_desc_ld_update(struct rte_bbdev_dec_op *op,
> >   	desc->op_addr = op;
> >   }
> >
> > +/* Enqueue one encode operations for ACC200 device in CB mode */
> > +static inline int enqueue_enc_one_op_cb(struct acc_queue *q, struct
> > +rte_bbdev_enc_op *op,
> > +		uint16_t total_enqueued_cbs)
> > +{
> > +	union acc_dma_desc *desc = NULL;
> > +	int ret;
> > +	uint32_t in_offset, out_offset, out_length, mbuf_total_left,
> > +		seg_total_left;
> > +	struct rte_mbuf *input, *output_head, *output;
> > +
> > +	uint16_t desc_idx = ((q->sw_ring_head + total_enqueued_cbs)
> > +			& q->sw_ring_wrap_mask);
> > +	desc = q->ring_addr + desc_idx;
> > +	acc_fcw_te_fill(op, &desc->req.fcw_te);
> > +
> > +	input = op->turbo_enc.input.data;
> > +	output_head = output = op->turbo_enc.output.data;
> > +	in_offset = op->turbo_enc.input.offset;
> > +	out_offset = op->turbo_enc.output.offset;
> > +	out_length = 0;
> > +	mbuf_total_left = op->turbo_enc.input.length;
> > +	seg_total_left = rte_pktmbuf_data_len(op->turbo_enc.input.data)
> > +			- in_offset;
> > +
> > +	ret = acc200_dma_desc_te_fill(op, &desc->req, &input, output,
> > +			&in_offset, &out_offset, &out_length,
> &mbuf_total_left,
> > +			&seg_total_left, 0);
> > +
> > +	if (unlikely(ret < 0))
> > +		return ret;
> > +
> > +	mbuf_append(output_head, output, out_length);
> > +
> > +#ifdef RTE_LIBRTE_BBDEV_DEBUG
> > +	rte_memdump(stderr, "FCW", &desc->req.fcw_te,
> > +			sizeof(desc->req.fcw_te) - 8);
> > +	rte_memdump(stderr, "Req Desc.", desc, sizeof(*desc)); #endif
> > +	/* One CB (one op) was successfully prepared to enqueue */
> > +	return 1;
> > +}
> > +
> >   /* Enqueue one encode operations for ACC200 device in CB mode
> >    * multiplexed on the same descriptor.
> >    */
> > @@ -1146,6 +1494,78 @@ enqueue_ldpc_enc_part_tb(struct acc_queue
> *q,
> > struct rte_bbdev_enc_op *op,
> >
> >   }
> >
> > +/* Enqueue one encode operations for ACC200 device in TB mode. */
> > +static inline int enqueue_enc_one_op_tb(struct acc_queue *q, struct
> > +rte_bbdev_enc_op *op,
> > +		uint16_t total_enqueued_cbs, uint8_t cbs_in_tb) {
> > +	union acc_dma_desc *desc = NULL;
> > +	int ret;
> > +	uint8_t r, c;
> > +	uint32_t in_offset, out_offset, out_length, mbuf_total_left,
> > +		seg_total_left;
> > +	struct rte_mbuf *input, *output_head, *output;
> > +	uint16_t current_enqueued_cbs = 0;
> > +
> > +	uint16_t desc_idx = ((q->sw_ring_head + total_enqueued_cbs)
> > +			& q->sw_ring_wrap_mask);
> 
> Maybe I did not make the comment on this patch specifically, but having a
> helper to get the descriptor index would make sense givent it is duplicated at
> several places.
> 
> 
> With this fixed, you can add:

It is a good idea, notably for readability. But unsure we need it now for 22.11 with still a lot of acc100 and acc200 commits in flight. 
Are you okay if we to defer this small refactor to 23.03? 
There are few similar routines which may benefit from similar wrapper functions. 
Let me know what you think. 

> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Thanks,
> Maxime