[dpdk-dev] [RFC PATCH 1/2] ethdev: add function to adjust number of descriptors

[Thomas Monjalon]

Hi,

02/03/2017 14:05, Andrew Rybchenko:
> From: Roman Zhukov <Roman.Zhukov at oktetlabs.ru>
> 
> Check that numbers of Rx and Tx descriptors satisfy descriptors limits
> from the Ethernet device information, otherwise adjust them to boundaries.
> 
> Signed-off-by: Roman Zhukov <Roman.Zhukov at oktetlabs.ru>
> Signed-off-by: Andrew Rybchenko <arybchenko at solarflare.com>

I think this helper is OK.
We could add it in 17.08.

Is there any comment from PMD maintainers?

[...]
> +static void
> +rte_eth_dev_adjust_nb_desc(uint16_t *nb_desc,
> +			   const struct rte_eth_desc_lim *desc_lim)
> +{
> +	if (desc_lim->nb_align != 0)
> +		*nb_desc = RTE_ALIGN_CEIL(*nb_desc, desc_lim->nb_align);
> +
> +	if (desc_lim->nb_max != 0)
> +		*nb_desc = RTE_MIN(*nb_desc, desc_lim->nb_max);
> +
> +	*nb_desc = RTE_MAX(*nb_desc, desc_lim->nb_min);
> +}
> +
> +int
> +rte_eth_dev_adjust_nb_rx_tx_desc(uint8_t port_id,
> +				 uint16_t *nb_rx_desc,
> +				 uint16_t *nb_tx_desc)
> +{
> +	struct rte_eth_dev *dev;
> +	struct rte_eth_dev_info dev_info;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +
> +	dev = &rte_eth_devices[port_id];
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_infos_get, -ENOTSUP);
> +
> +	rte_eth_dev_info_get(port_id, &dev_info);
> +
> +	if (nb_rx_desc != NULL)
> +		rte_eth_dev_adjust_nb_desc(nb_rx_desc, &dev_info.rx_desc_lim);
> +
> +	if (nb_tx_desc != NULL)
> +		rte_eth_dev_adjust_nb_desc(nb_tx_desc, &dev_info.tx_desc_lim);
> +
> +	return 0;
> +}
[...]
> +/**
> + * Check that numbers of Rx and Tx descriptors satisfy descriptors limits from
> + * the ethernet device information, otherwise adjust them to boundaries.
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param nb_rx_desc
> + *   A pointer to a uint16_t where the number of receive
> + *   descriptors stored.
> + * @param nb_tx_desc
> + *   A pointer to a uint16_t where the number of transmit
> + *   descriptors stored.
> + * @return
> + *   - (0) if successful.
> + *   - (-ENOTSUP, -ENODEV or -EINVAL) on failure.
> + */
> +int rte_eth_dev_adjust_nb_rx_tx_desc(uint8_t port_id,
> +				     uint16_t *nb_rx_desc,
> +				     uint16_t *nb_tx_desc);
> +