[dpdk-dev,5/6] net/mlx5: implement descriptor status API

  Since there is no "descriptor done" flag like on Intel drivers, the
approach is different on mlx5 driver.
- for Tx, we call txq_complete() to free descriptors processed by
  the hw, then we check if the descriptor is between tail and head
- for Rx, we need to browse the cqes, managing compressed ones,
  to get the number of used descriptors.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 drivers/net/mlx5/mlx5.c      |  2 ++
 drivers/net/mlx5/mlx5_rxtx.c | 83 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/net/mlx5/mlx5_rxtx.h |  2 ++
 3 files changed, 87 insertions(+)
  

Hi Olivier,

On Wed, Mar 01, 2017 at 06:19:11PM +0100, Olivier Matz wrote:
> Since there is no "descriptor done" flag like on Intel drivers, the
> approach is different on mlx5 driver.
> - for Tx, we call txq_complete() to free descriptors processed by
>   the hw, then we check if the descriptor is between tail and head
> - for Rx, we need to browse the cqes, managing compressed ones,
>   to get the number of used descriptors.
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>  drivers/net/mlx5/mlx5.c      |  2 ++
>  drivers/net/mlx5/mlx5_rxtx.c | 83 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/net/mlx5/mlx5_rxtx.h |  2 ++
>  3 files changed, 87 insertions(+)
> 
> diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
> index d4bd469..4a6450c 100644
> --- a/drivers/net/mlx5/mlx5.c
> +++ b/drivers/net/mlx5/mlx5.c
> @@ -222,6 +222,8 @@ static const struct eth_dev_ops mlx5_dev_ops = {
>  	.rss_hash_update = mlx5_rss_hash_update,
>  	.rss_hash_conf_get = mlx5_rss_hash_conf_get,
>  	.filter_ctrl = mlx5_dev_filter_ctrl,
> +	.rx_descriptor_status = mlx5_rx_descriptor_status,
> +	.tx_descriptor_status = mlx5_tx_descriptor_status,
>  };
>  
>  static struct {
> diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
> index 88b0354..b3375f6 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.c
> +++ b/drivers/net/mlx5/mlx5_rxtx.c
> @@ -345,6 +345,89 @@ mlx5_tx_dbrec(struct txq *txq, volatile struct mlx5_wqe *wqe)
>  }
>  
>  /**
> + * DPDK callback to check the status of a tx descriptor.
> + *
> + * @param dev
> + *   Pointer to Ethernet device structure.
> + * @param[in] tx_queue_id
> + *   The identifier of the tx queue.
> + * @param[in] offset
> + *   The index of the descriptor in the ring.
> + *
> + * @return
> + *   The status of the tx descriptor.
> + */
> +int
> +mlx5_tx_descriptor_status(struct rte_eth_dev *dev, uint16_t tx_queue_id,
> +			  uint16_t offset)
> +{
> +	struct txq *txq = dev->data->tx_queues[tx_queue_id];
> +	const unsigned int elts_n = 1 << txq->elts_n;
> +	const unsigned int elts_cnt = elts_n - 1;
> +	unsigned int used;
> +
> +	txq_complete(txq);
> +

If you submit a v2 please remove this empty line.

> +	used = (txq->elts_head - txq->elts_tail) & elts_cnt;
> +	if (offset < used)
> +		return RTE_ETH_TX_DESC_FULL;
> +	return RTE_ETH_TX_DESC_DONE;
> +}
> +
> +/**
> + * DPDK callback to check the status of a rx descriptor.
> + *
> + * @param dev
> + *   Pointer to Ethernet device structure.
> + * @param[in] tx_queue_id
> + *   The identifier of the rx queue.
> + * @param[in] offset
> + *   The index of the descriptor in the ring.
> + *
> + * @return
> + *   The status of the rx descriptor.
> + */
> +int
> +mlx5_rx_descriptor_status(struct rte_eth_dev *dev, uint16_t rx_queue_id,
> +			  uint16_t offset)
> +{
> +	struct rxq *rxq = dev->data->rx_queues[rx_queue_id];
> +	struct rxq_zip *zip = &rxq->zip;
> +	volatile struct mlx5_cqe *cqe;
> +	const unsigned int cqe_n = (1 << rxq->cqe_n);
> +	const unsigned int cqe_cnt = cqe_n - 1;
> +	unsigned int cq_ci;
> +	unsigned int used;
> +
> +	/* if we are processing a compressed cqe */
> +	if (zip->ai) {
> +		used = zip->cqe_cnt - zip->ca;
> +		cq_ci = zip->cq_ci;
> +	} else {
> +		used = 0;
> +		cq_ci = rxq->cq_ci;
> +	}
> +	cqe = &(*rxq->cqes)[cq_ci & cqe_cnt];
> +	while (check_cqe(cqe, cqe_n, cq_ci) == 0) {
> +		int8_t op_own;
> +		unsigned int n;
> +
> +		op_own = cqe->op_own;
> +		if (MLX5_CQE_FORMAT(op_own) == MLX5_COMPRESSED)
> +			n = ntohl(cqe->byte_cnt);
> +		else
> +			n = 1;
> +		cq_ci += n;
> +		used += n;
> +		cqe = &(*rxq->cqes)[cq_ci & cqe_cnt];
> +	}
> +	used = RTE_MIN(used, (1U << rxq->elts_n) - 1);
> +	if (offset < used)
> +		return RTE_ETH_RX_DESC_DONE;
> +	return RTE_ETH_RX_DESC_AVAIL;
> +}
> +
> +/**
>   * DPDK callback for TX.
>   *
>   * @param dpdk_txq
> diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
> index 41a34d7..e864dcd 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.h
> +++ b/drivers/net/mlx5/mlx5_rxtx.h
> @@ -323,6 +323,8 @@ uint16_t mlx5_tx_burst_mpw_inline(void *, struct rte_mbuf **, uint16_t);
>  uint16_t mlx5_rx_burst(void *, struct rte_mbuf **, uint16_t);
>  uint16_t removed_tx_burst(void *, struct rte_mbuf **, uint16_t);
>  uint16_t removed_rx_burst(void *, struct rte_mbuf **, uint16_t);
> +int mlx5_rx_descriptor_status(struct rte_eth_dev *, uint16_t, uint16_t);
> +int mlx5_tx_descriptor_status(struct rte_eth_dev *, uint16_t, uint16_t);
>  
>  /* mlx5_mr.c */
>  
> -- 
> 2.8.1


Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>