ethdev: update xstats by ID driver callbacks documentation

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.

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>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
index cc2c752..81dee87 100644 (file)
--- a/lib/ethdev/ethdev_driver.h
+++ b/lib/ethdev/ethdev_driver.h
@@ -183,11 +183,28 @@ 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
@@ -214,10 +231,27 @@ 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.
+ *
+ * @param dev
+ *   ethdev handle of port.
+ * @param xstats_names
+ *   An rte_eth_xstat_name array of at least @p size elements to be filled.
+ *   Must not be NULL.
+ * @param ids
+ *   IDs array to retrieve specific statistics. Must not be NULL.
+ * @param size
+ *   Element count in @p ids and @p xstats_names.
+ *
+ * @return
+ *   - A number of filled in stats.
+ *   - 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,