[PATCH 1/2] net/cnxk: optimize flow control hysteresis

[pbhagavatula at marvell.com]

From: Pavan Nikhilesh <pbhagavatula at marvell.com>

Set flow control hysteresis to ignore immediate sequence of
decrement-increment to avoid unnecessary LLC traffic.
Enable hysteresis when SQ length is more than 512 as it lower
queue lengths will require faster updates.

Signed-off-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
Signed-off-by: Satha Rao <skoteshwar at marvell.com>
---
 drivers/net/cnxk/cnxk_ethdev.c | 2 ++
 drivers/net/cnxk/cnxk_ethdev.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/cnxk/cnxk_ethdev.c b/drivers/net/cnxk/cnxk_ethdev.c
index 1cae3084e1..42a52ed0ca 100644
--- a/drivers/net/cnxk/cnxk_ethdev.c
+++ b/drivers/net/cnxk/cnxk_ethdev.c
@@ -487,6 +487,8 @@ cnxk_nix_tx_queue_setup(struct rte_eth_dev *eth_dev, uint16_t qid,
 	sq->qid = qid;
 	sq->nb_desc = nb_desc;
 	sq->max_sqe_sz = nix_sq_max_sqe_sz(dev);
+	if (sq->nb_desc >= CNXK_NIX_DEF_SQ_COUNT)
+		sq->fc_hyst_bits = 0x1;
 
 	if (nix->tx_compl_ena) {
 		sq->cqid = sq->qid + dev->nb_rxq;
diff --git a/drivers/net/cnxk/cnxk_ethdev.h b/drivers/net/cnxk/cnxk_ethdev.h
index 62a06e5d03..97537de17a 100644
--- a/drivers/net/cnxk/cnxk_ethdev.h
+++ b/drivers/net/cnxk/cnxk_ethdev.h
@@ -49,6 +49,8 @@
 /* LPB & SPB */
 #define CNXK_NIX_NUM_POOLS_MAX 2
 
+#define CNXK_NIX_DEF_SQ_COUNT	512
+
 #define CNXK_NIX_RSS_L3_L4_SRC_DST                                             \
 	(RTE_ETH_RSS_L3_SRC_ONLY | RTE_ETH_RSS_L3_DST_ONLY |                   \
 	 RTE_ETH_RSS_L4_SRC_ONLY | RTE_ETH_RSS_L4_DST_ONLY)
-- 
2.25.1