[PATCH] cryptodev: clarify error codes returned

[Anoob Joseph]

When symmetric sessions are created, it may fail due to non-critical
errors. When PMD doesn't support the specific combination that
application requested, it can return -ENOTSUP which can be handled so in
application. The API is already setting rte_errno according to the
reason of the failure. Clarifying this in the spec to list down possible
error codes.

Fixes: bdce2564dbf7 ("cryptodev: rework session framework")

Signed-off-by: Anoob Joseph <anoobj at marvell.com>
---
 lib/cryptodev/rte_cryptodev.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/cryptodev/rte_cryptodev.h b/lib/cryptodev/rte_cryptodev.h
index 3a9ad13660..4e3a7db0fe 100644
--- a/lib/cryptodev/rte_cryptodev.h
+++ b/lib/cryptodev/rte_cryptodev.h
@@ -1048,11 +1048,14 @@ rte_cryptodev_asym_session_pool_create(const char *name, uint32_t nb_elts,
  * @param   dev_id   ID of device that we want the session to be used on
  * @param   xforms   Symmetric crypto transform operations to apply on flow
  *                   processed with this session
- * @param   mp       Mempool where the private data is allocated.
+ * @param   mp       Mempool to allocate symmetric session objects from
  *
  * @return
  *  - On success return pointer to sym-session.
- *  - On failure returns NULL.
+ *  - On failure returns NULL and rte_errno is set to the error code.
+ *     EINVAL on invalid arguments.
+ *     ENOMEM on memory error for session allocation.
+ *     ENOTSUP if device doesn't support session configuration.
  */
 void *
 rte_cryptodev_sym_session_create(uint8_t dev_id,
-- 
2.25.1