[dpdk-stable] [PATCH v4 2/2] ethdev: fix docs of drivers callbacks getting xstats by IDs

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

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(-)

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,
-- 
2.30.2