[v3,04/11] ethdev: fix docs of drivers callbacks getting xstats by IDs

  From: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>

Update xstats by IDs callbacks documentation in accordance with
ethdev usage of these callbacks. Document valid combinations of
input arguments to make driver implementation simpler.

Fixes: 79c913a42f0 ("ethdev: retrieve xstats by ID")
Cc: stable@dpdk.org

Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>
---
 lib/ethdev/ethdev_driver.h | 43 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)
  

On 7/23/2021 2:15 PM, Andrew Rybchenko wrote:
> From: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
> 
> Update xstats by IDs callbacks documentation in accordance with
> ethdev usage of these callbacks. Document valid combinations of
> input arguments to make driver implementation simpler.
> 
> Fixes: 79c913a42f0 ("ethdev: retrieve xstats by ID")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> Reviewed-by: Andy Moreton <amoreton@xilinx.com>
> ---
>  lib/ethdev/ethdev_driver.h | 43 ++++++++++++++++++++++++++++++++++++--
>  1 file changed, 41 insertions(+), 2 deletions(-)
> 

Some discussion on the v1 is still valid here, so I am not putting same comments
here until v1 ones clarified.

> diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
> index 40e474aa7e..fd5b7ca550 100644
> --- a/lib/ethdev/ethdev_driver.h
> +++ b/lib/ethdev/ethdev_driver.h
> @@ -187,11 +187,28 @@ typedef int (*eth_xstats_get_t)(struct rte_eth_dev *dev,
>  	struct rte_eth_xstat *stats, unsigned int n);
>  /**< @internal Get extended stats of an Ethernet device. */
>  
> +/**
> + * @internal
> + * Get extended stats of an Ethernet device.
> + *
> + * @param dev
> + *   ethdev handle of port.
> + * @param ids
> + *   IDs array to retrieve specific statistics. Must not be NULL.
> + * @param values
> + *   A pointer to a table to be filled with device statistics values.
> + *   Must not be NULL.
> + * @param n
> + *   Element count in @p ids and @p values
> + *
> + * @return
> + *   - A number of filled in stats.
> + *   - A negative value on error.
> + */
>  typedef int (*eth_xstats_get_by_id_t)(struct rte_eth_dev *dev,
>  				      const uint64_t *ids,
>  				      uint64_t *values,
>  				      unsigned int n);
> -/**< @internal Get extended stats of an Ethernet device. */
>  
>  /**
>   * @internal
> @@ -218,10 +235,32 @@ typedef int (*eth_xstats_get_names_t)(struct rte_eth_dev *dev,
>  	struct rte_eth_xstat_name *xstats_names, unsigned int size);
>  /**< @internal Get names of extended stats of an Ethernet device. */
>  
> +/**
> + * @internal
> + * Get names of extended stats of an Ethernet device.
> + * For name count, set @p xstats_names and @p ids to NULL.
> + *
> + * @param dev
> + *   ethdev handle of port.
> + * @param xstats_names
> + *   An rte_eth_xstat_name array of at least *size* elements to
> + *   be filled. Can be NULL together with @p ids to retrieve number of
> + *   available statistics.
> + * @param ids
> + *   IDs array to retrieve specific statistics. Can be NULL together
> + *   with @p xstats_names to retrieve number of available statistics.
> + * @param size
> + *   Size of ids and xstats_names arrays.
> + *   Element count in @p ids and @p xstats_names
> + *
> + * @return
> + *   - A number of filled in stats if both xstats_names and ids are not NULL.
> + *   - A number of available stats if both xstats_names and ids are NULL.
> + *   - A negative value on error.
> + */
>  typedef int (*eth_xstats_get_names_by_id_t)(struct rte_eth_dev *dev,
>  	struct rte_eth_xstat_name *xstats_names, const uint64_t *ids,
>  	unsigned int size);
> -/**< @internal Get names of extended stats of an Ethernet device. */
>  
>  typedef int (*eth_queue_stats_mapping_set_t)(struct rte_eth_dev *dev,
>  					     uint16_t queue_id,
>