[PATCH 2/2] net/bnxt: fix epoch bit calculation

[Ajit Khaparde <ajit.khaparde@broadcom.com>]

The epoch bit is a binary value which needs to be toggled with
every pass of the ring in the hardware.
The code was doing this prematurely in vector path.
Improve the ring wrap identification and fix epoch bit calculation
in the vector path.

Fixes: 30656a1cace8 ("net/bnxt: refactor epoch setting")
Cc: stable@dpdk.org

Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Damodharam Ammepalli <damodharam.ammepalli@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
---
 drivers/net/bnxt/bnxt_ring.h            | 19 +++++++++++++++++++
 drivers/net/bnxt/bnxt_rxq.c             |  1 +
 drivers/net/bnxt/bnxt_rxq.h             |  1 +
 drivers/net/bnxt/bnxt_rxr.c             |  4 ++++
 drivers/net/bnxt/bnxt_rxtx_vec_common.h | 11 +++++------
 5 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/net/bnxt/bnxt_ring.h b/drivers/net/bnxt/bnxt_ring.h
index a7470a0e73..3e2bd634a8 100644
--- a/drivers/net/bnxt/bnxt_ring.h
+++ b/drivers/net/bnxt/bnxt_ring.h
@@ -108,6 +108,25 @@ static inline void bnxt_db_write(struct bnxt_db_info *db, uint32_t idx)
 	}
 }
 
+static inline void bnxt_db_epoch_write(struct bnxt_db_info *db, uint32_t idx, uint32_t epoch)
+{
+	uint32_t db_idx = DB_RING_IDX(db, idx);
+	void *doorbell = db->doorbell;
+
+	if (db->db_64) {
+		uint64_t key_idx = db->db_key64 | db_idx;
+
+		key_idx |= epoch << DBR_EPOCH_SFT;
+
+		rte_compiler_barrier();
+		rte_write64_relaxed(key_idx, doorbell);
+	} else {
+		uint32_t key_idx = db->db_key32 | db_idx;
+
+		rte_write32(key_idx, doorbell);
+	}
+}
+
 static inline void bnxt_db_mpc_write(struct bnxt_db_info *db, uint32_t idx, uint32_t epoch)
 {
 	uint32_t db_idx = DB_RING_IDX(db, idx);
diff --git a/drivers/net/bnxt/bnxt_rxq.c b/drivers/net/bnxt/bnxt_rxq.c
index a1c3777f33..91b3555df6 100644
--- a/drivers/net/bnxt/bnxt_rxq.c
+++ b/drivers/net/bnxt/bnxt_rxq.c
@@ -425,6 +425,7 @@ int bnxt_rx_queue_setup_op(struct rte_eth_dev *eth_dev,
 		goto err;
 	}
 	rxq->rx_mbuf_alloc_fail = 0;
+	rxq->epoch = 0;
 
 	/* rxq 0 must not be stopped when used as async CPR */
 	if (!BNXT_NUM_ASYNC_CPR(bp) && queue_idx == 0)
diff --git a/drivers/net/bnxt/bnxt_rxq.h b/drivers/net/bnxt/bnxt_rxq.h
index cd49faf4cf..3385496e70 100644
--- a/drivers/net/bnxt/bnxt_rxq.h
+++ b/drivers/net/bnxt/bnxt_rxq.h
@@ -30,6 +30,7 @@ struct bnxt_rx_queue {
 	uint16_t		rxrearm_nb; /* number of descs to reinit. */
 	uint16_t		rxrearm_start; /* next desc index to reinit. */
 #endif
+	uint32_t		epoch;
 	uint16_t		port_id; /* Device port identifier */
 	uint8_t			crc_len; /* 0 if CRC stripped, 4 otherwise */
 	uint8_t			rx_deferred_start; /* not in global dev start */
diff --git a/drivers/net/bnxt/bnxt_rxr.c b/drivers/net/bnxt/bnxt_rxr.c
index b53d9a917a..c94abefa01 100644
--- a/drivers/net/bnxt/bnxt_rxr.c
+++ b/drivers/net/bnxt/bnxt_rxr.c
@@ -1366,6 +1366,10 @@ uint16_t bnxt_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 			bnxt_db_write(&rxr->rx_db, rxr->rx_raw_prod);
 			rxq->rxrearm_start++;
 			rxq->rxrearm_nb--;
+			if (rxq->rxrearm_start >= rxq->nb_rx_desc) {
+				rxq->rxrearm_start = 0;
+				rxq->epoch = rxq->epoch == 0 ? 1 : 0;
+			}
 		} else {
 			/* Retry allocation on next call. */
 			break;
diff --git a/drivers/net/bnxt/bnxt_rxtx_vec_common.h b/drivers/net/bnxt/bnxt_rxtx_vec_common.h
index f608b5152e..e185005293 100644
--- a/drivers/net/bnxt/bnxt_rxtx_vec_common.h
+++ b/drivers/net/bnxt/bnxt_rxtx_vec_common.h
@@ -50,6 +50,7 @@ bnxt_rxq_vec_setup_common(struct bnxt_rx_queue *rxq)
 	rxq->mbuf_initializer = *(uint64_t *)p;
 	rxq->rxrearm_nb = 0;
 	rxq->rxrearm_start = 0;
+	rxq->epoch = 1;
 	return 0;
 }
 
@@ -88,13 +89,11 @@ bnxt_rxq_rearm(struct bnxt_rx_queue *rxq, struct bnxt_rx_ring_info *rxr)
 	}
 
 	rxq->rxrearm_start += nb;
-	/*
-	 * We can pass rxq->rxrearm_star - 1 as well, but then the epoch
-	 * bit calculation is messed up.
-	 */
-	bnxt_db_write(&rxr->rx_db, rxr->rx_raw_prod);
-	if (rxq->rxrearm_start >= rxq->nb_rx_desc)
+	bnxt_db_epoch_write(&rxr->rx_db, rxq->rxrearm_start - 1, rxq->epoch);
+	if (rxq->rxrearm_start >= rxq->nb_rx_desc) {
 		rxq->rxrearm_start = 0;
+		rxq->epoch = rxq->epoch == 0 ? 1 : 0;
+	}
 
 	rxq->rxrearm_nb -= nb;
 }
-- 
2.39.5 (Apple Git-154)