net/bnxt: fix max rings computation

[ upstream commit c72fe7a ]

The current max_rings computation does not take into account the case
when max_nq_rings is <= num_async_cpr. This results in a wrong value
like 0, when max_nq_rings is 1. Fix this by subtracting num_async_cpr
only when max_cp_rings > num_async_cpr.

Apart from this, the entire logic is currently spread across a few
macros, making it hard to read and debug this code. Move this code
into an inline function.

max_msix is not used in the max_rings calculation.
Apparently the max_msix field returned in HWRM_RESC_QCAPS is only valid
for Thor and newer chips. On Wh+ it will be equal to min_compl_rings.
Also, when a function reset is performed on an application quit, FW
will not reset the VF resource pool as per design.
This can lead to a strange condition wherein the max_msix field
on Wh+ keeps changing on each application re-load thereby throwing
throwing off the max_rings computation.

Fixes: f03e66c ("net/bnxt: limit queue count for NS3/Stingray devices")

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>

drivers/net/bnxt/bnxt.h

@@ -620,19 +620,6 @@ struct bnxt {
 	uint16_t		max_tx_rings;
 	uint16_t		max_rx_rings;
 #define MAX_STINGRAY_RINGS		128U
-/* For sake of symmetry, max Tx rings == max Rx rings, one stat ctx for each */
-#define BNXT_MAX_RX_RINGS(bp) \
-	(BNXT_STINGRAY(bp) ? RTE_MIN(RTE_MIN(bp->max_rx_rings / 2U, \
-					     MAX_STINGRAY_RINGS), \
-				     bp->max_stat_ctx / 2U) : \
-				RTE_MIN(bp->max_rx_rings / 2U, \
-					bp->max_stat_ctx / 2U))
-#define BNXT_MAX_TX_RINGS(bp) \
-	(RTE_MIN((bp)->max_tx_rings, BNXT_MAX_RX_RINGS(bp)))
-
-#define BNXT_MAX_RINGS(bp) \
-	(RTE_MIN((((bp)->max_cp_rings - BNXT_NUM_ASYNC_CPR(bp)) / 2U), \
-		 BNXT_MAX_TX_RINGS(bp)))
 	uint16_t		max_nq_rings;
 	uint16_t		max_l2_ctx;
 	uint16_t		max_rx_em_flows;
@@ -668,6 +655,34 @@ struct bnxt {
 	struct bnxt_error_recovery_info *recovery_info;
 };
 
+static
+inline uint16_t bnxt_max_rings(struct bnxt *bp)
+{
+	uint16_t max_tx_rings = bp->max_tx_rings;
+	uint16_t max_rx_rings = bp->max_rx_rings;
+	uint16_t max_cp_rings = bp->max_cp_rings;
+	uint16_t max_rings;
+
+	/* For the sake of symmetry:
+	 * max Tx rings == max Rx rings, one stat ctx for each.
+	 */
+	if (BNXT_STINGRAY(bp)) {
+		max_rx_rings = RTE_MIN(RTE_MIN(max_rx_rings / 2U,
+					       MAX_STINGRAY_RINGS),
+				       bp->max_stat_ctx / 2U);
+	} else {
+		max_rx_rings = RTE_MIN(max_rx_rings / 2U,
+				       bp->max_stat_ctx / 2U);
+	}
+
+	max_tx_rings = RTE_MIN(max_tx_rings, max_rx_rings);
+	if (max_cp_rings > BNXT_NUM_ASYNC_CPR(bp))
+		max_cp_rings -= BNXT_NUM_ASYNC_CPR(bp);
+	max_rings = RTE_MIN(max_cp_rings / 2U, max_tx_rings);
+
+	return max_rings;
+}
+
 int bnxt_mtu_set_op(struct rte_eth_dev *eth_dev, uint16_t new_mtu);
 int bnxt_link_update(struct rte_eth_dev *eth_dev, int wait_to_complete,
 		     bool exp_link_status);

drivers/net/bnxt/bnxt_ethdev.c

@@ -526,7 +526,7 @@ static int bnxt_dev_info_get_op(struct rte_eth_dev *eth_dev,
 	if (BNXT_PF(bp))
 		dev_info->max_vfs = pdev->max_vfs;
 
-	max_rx_rings = BNXT_MAX_RINGS(bp);
+	max_rx_rings = bnxt_max_rings(bp);
 	/* For the sake of symmetry, max_rx_queues = max_tx_queues */
 	dev_info->max_rx_queues = max_rx_rings;
 	dev_info->max_tx_queues = max_rx_rings;

drivers/net/bnxt/bnxt_rxq.c

@@ -304,7 +304,7 @@ int bnxt_rx_queue_setup_op(struct rte_eth_dev *eth_dev,
 	if (rc)
 		return rc;
 
-	if (queue_idx >= BNXT_MAX_RINGS(bp)) {
+	if (queue_idx >= bnxt_max_rings(bp)) {
 		PMD_DRV_LOG(ERR,
 			"Cannot create Rx ring %d. Only %d rings available\n",
 			queue_idx, bp->max_rx_rings);
@@ -356,8 +356,9 @@ int bnxt_rx_queue_setup_op(struct rte_eth_dev *eth_dev,
 
 	eth_dev->data->rx_queues[queue_idx] = rxq;
 	/* Allocate RX ring hardware descriptors */
-	if (bnxt_alloc_rings(bp, queue_idx, NULL, rxq, rxq->cp_ring, NULL,
-			     "rxr")) {
+	rc = bnxt_alloc_rings(bp, queue_idx, NULL, rxq, rxq->cp_ring, NULL,
+			     "rxr");
+	if (rc) {
 		PMD_DRV_LOG(ERR,
 			    "ring_dma_zone_reserve for rx_ring failed!\n");
 		goto err;

drivers/net/bnxt/bnxt_txq.c

@@ -98,7 +98,7 @@ int bnxt_tx_queue_setup_op(struct rte_eth_dev *eth_dev,
 	if (rc)
 		return rc;
 
-	if (queue_idx >= BNXT_MAX_RINGS(bp)) {
+	if (queue_idx >= bnxt_max_rings(bp)) {
 		PMD_DRV_LOG(ERR,
 			"Cannot create Tx ring %d. Only %d rings available\n",
 			queue_idx, bp->max_tx_rings);