[PATCH] doc: update match with compare result item limitation

[Suanming Mou]

In switch mode, when ``repr_matching_en`` flag is enabled in the devarg,
the match with compare result item is not supported to the ``ingress``
rule as an implicit REPRESENTED_PORT need to be added to the matcher.
That REPRESENTED_PORT item conflicts with the single item limitation for
match with compare result item.

Fixes: cb25df7ce9d6 ("net/mlx5: support comparison matching")
Cc: stable at dpdk.org

Signed-off-by: Suanming Mou <suanmingm at nvidia.com>
---
 doc/guides/nics/mlx5.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 7ced6ca8f9..43ae9070ab 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -460,6 +460,11 @@ Limitations
   - The field type ``RTE_FLOW_FIELD_VALUE`` must be the base (``b``) field.
   - The field type ``RTE_FLOW_FIELD_RANDOM`` can only be compared with
     ``RTE_FLOW_FIELD_VALUE``.
+  - In switch mode, when ``repr_matching_en`` flag is enabled in the devarg,
+    the match with compare result item is not supported to the ``ingress``
+    rule as an implicit REPRESENTED_PORT need to be added to the matcher.
+    That REPRESENTED_PORT item conflicts with the single item limitation for
+    match with compare result item.
 
 - No Tx metadata go to the E-Switch steering domain for the Flow group 0.
   The flows within group 0 and set metadata action are rejected by hardware.
-- 
2.34.1