[dpdk-dev] [PATCH v3 2/2] net/mlx5: fix Rx descriptor status returned value

[Maxime Leroy]

From: Didier Pallard <didier.pallard at 6wind.com>

Three bugs in rx_queue_count function:
- One entry may contain several segments, so 'used' must be multiplied
  by number of segments per entry to properly reflect the queue usage.
- The number of cqes is equals to (1U << rxq->elts_n) - 1 in non mqrt
  mode. The range returned by rx_queue_count should be the number of
  entries used in queue, so it ranges from 0 to max number of entries
  in queue, not this number minus one.
- For MQRT mode, we need to take acount of the number of strd.

Fixes: 8788fec1f269 ("net/mlx5: implement descriptor status API")
Signed-off-by: Didier Pallard <didier.pallard at 6wind.com>
Signed-off-by: Maxime Leroy <maxime.leroy at 6wind.com>
---
 drivers/net/mlx5/mlx5_rxtx.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 2733dcd3..2ecf901f 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -463,6 +463,9 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
 	struct rxq_zip *zip = &rxq->zip;
 	volatile struct mlx5_cqe *cqe;
 	const unsigned int cqe_n = (1 << rxq->cqe_n);
+	const unsigned int sges_n = (1 << rxq->sges_n);
+	const unsigned int elts_n = (1 << rxq->elts_n);
+	const unsigned int strd_n = (1 << rxq->strd_num_n);
 	const unsigned int cqe_cnt = cqe_n - 1;
 	unsigned int cq_ci, used;
 
@@ -488,7 +491,7 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
 		used += n;
 		cqe = &(*rxq->cqes)[cq_ci & cqe_cnt];
 	}
-	used = RTE_MIN(used, cqe_n);
+	used = RTE_MIN(used * sges_n, elts_n * strd_n);
 	return used;
 }
 
-- 
2.27.0