[PATCH v4] doc: fix flow validate comments

[John Daley <johndale@cisco.com>]

Change comments for rte_flow_validate() function to indicate that flow
rule collision and resource validation is optional for PMDs and
therefore the return codes may have different meanings.

Fixes: b1a4b4cbc0a8 ("ethdev: introduce generic flow API")

Signed-off-by: John Daley <johndale@cisco.com>
---
v2: another crack at the comments
v3: fix typos, rewording, put back a sentence omitted in v2
v4: fixes per Adrien Mazarguil- update guide, typo, commit title

 doc/guides/prog_guide/rte_flow.rst | 17 ++++++++++++-----
 lib/librte_ether/rte_flow.h        | 16 +++++++++++-----
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
index 5ee045ee8..9f3d3b096 100644
--- a/doc/guides/prog_guide/rte_flow.rst
+++ b/doc/guides/prog_guide/rte_flow.rst
@@ -1332,9 +1332,11 @@ supported and can be created.
                      const struct rte_flow_action actions[],
                      struct rte_flow_error *error);
 
-While this function has no effect on the target device, the flow rule is
-validated against its current configuration state and the returned value
-should be considered valid by the caller for that state only.
+The flow rule is validated for correctness and whether it could be accepted
+by the device given sufficient resources. The rule is checked against the
+current device mode and queue configuration. The flow rule may also
+optionally be validated against existing flow rules and device resources.
+This function has no effect on the target device.
 
 The returned value is guaranteed to remain valid only as long as no
 successful calls to ``rte_flow_create()`` or ``rte_flow_destroy()`` are made
@@ -1360,8 +1362,13 @@ Return values:
 - ``-EINVAL``: unknown or invalid rule specification.
 - ``-ENOTSUP``: valid but unsupported rule specification (e.g. partial
   bit-masks are unsupported).
-- ``-EEXIST``: collision with an existing rule.
-- ``-ENOMEM``: not enough resources.
+- ``EEXIST``: collision with an existing rule. Only returned if device
+  supports flow rule collision checking and there was a flow rule
+  collision. Not receiving this return code is no guarantee that creating
+  the rule will not fail due to a collision.
+- ``ENOMEM``: not enough memory to execute the function, or if the device
+  supports resource validation, resource limitation on the device.
+
 - ``-EBUSY``: action cannot be performed due to busy device resources, may
   succeed if the affected queues or even the entire port are in a stopped
   state (see ``rte_eth_dev_rx_queue_stop()`` and ``rte_eth_dev_stop()``).
diff --git a/lib/librte_ether/rte_flow.h b/lib/librte_ether/rte_flow.h
index 8013ecab2..7749491cb 100644
--- a/lib/librte_ether/rte_flow.h
+++ b/lib/librte_ether/rte_flow.h
@@ -983,9 +983,11 @@ struct rte_flow_error {
 /**
  * Check whether a flow rule can be created on a given port.
  *
- * While this function has no effect on the target device, the flow rule is
- * validated against its current configuration state and the returned value
- * should be considered valid by the caller for that state only.
+ * The flow rule is validated for correctness and whether it could be accepted
+ * by the device given sufficient resources. The rule is checked against the
+ * current device mode and queue configuration. The flow rule may also
+ * optionally be validated against existing flow rules and device resources.
+ * This function has no effect on the target device.
  *
  * The returned value is guaranteed to remain valid only as long as no
  * successful calls to rte_flow_create() or rte_flow_destroy() are made in
@@ -1016,9 +1018,13 @@ struct rte_flow_error {
  *   -ENOTSUP: valid but unsupported rule specification (e.g. partial
  *   bit-masks are unsupported).
  *
- *   -EEXIST: collision with an existing rule.
+ *   -EEXIST: collision with an existing rule. Only returned if device
+ *   supports flow rule collision checking and there was a flow rule
+ *   collision. Not receiving this return code is no guarantee that creating
+ *   the rule will not fail due to a collision.
  *
- *   -ENOMEM: not enough resources.
+ *   -ENOMEM: not enough memory to execute the function, or if the device
+ *   supports resource validation, resource limitation on the device.
  *
  *   -EBUSY: action cannot be performed due to busy device resources, may
  *   succeed if the affected queues or even the entire port are in a stopped
-- 
2.12.0