bnxt_en: Handle no aggregation ring gracefully.

The current code assumes that we will always have at least 2 rx rings, 1
will be used as an aggregation ring for TPA and jumbo page placements.
However, it is possible, especially on a VF, that there is only 1 rx
ring available.  In this scenario, the current code will fail to initialize.
To handle it, we need to properly set up only 1 ring without aggregation.
Set a new flag BNXT_FLAG_NO_AGG_RINGS for this condition and add logic to
set up the chip to place RX data linearly into a single buffer per packet.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -2496,7 +2496,7 @@ void bnxt_set_ring_params(struct bnxt *bp)
 		agg_factor = min_t(u32, 4, 65536 / BNXT_RX_PAGE_SIZE);
 
 	bp->flags &= ~BNXT_FLAG_JUMBO;
-	if (rx_space > PAGE_SIZE) {
+	if (rx_space > PAGE_SIZE && !(bp->flags & BNXT_FLAG_NO_AGG_RINGS)) {
 		u32 jumbo_factor;
 
 		bp->flags |= BNXT_FLAG_JUMBO;
@@ -6174,6 +6174,9 @@ static int bnxt_set_features(struct net_device *dev, netdev_features_t features)
 	if (features & NETIF_F_LRO)
 		flags |= BNXT_FLAG_LRO;
 
+	if (bp->flags & BNXT_FLAG_NO_AGG_RINGS)
+		flags &= ~BNXT_FLAG_TPA;
+
 	if (features & NETIF_F_HW_VLAN_CTAG_RX)
 		flags |= BNXT_FLAG_STRIP_VLAN;
 
@@ -7039,9 +7042,18 @@ static int bnxt_get_dflt_rings(struct bnxt *bp, int *max_rx, int *max_tx,
 {
 	int rc;
 
+	rc = bnxt_get_max_rings(bp, max_rx, max_tx, shared);
+	if (rc && (bp->flags & BNXT_FLAG_AGG_RINGS)) {
+		/* Not enough rings, try disabling agg rings. */
+		bp->flags &= ~BNXT_FLAG_AGG_RINGS;
 		rc = bnxt_get_max_rings(bp, max_rx, max_tx, shared);
 		if (rc)
 			return rc;
+		bp->flags |= BNXT_FLAG_NO_AGG_RINGS;
+		bp->dev->hw_features &= ~NETIF_F_LRO;
+		bp->dev->features &= ~NETIF_F_LRO;
+		bnxt_set_ring_params(bp);
+	}
 
 	if (bp->flags & BNXT_FLAG_ROCE_CAP) {
 		int max_cp, max_stat, max_irq;
@@ -7236,7 +7248,12 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	bnxt_set_tpa_flags(bp);
 	bnxt_set_ring_params(bp);
 	bnxt_set_max_func_irqs(bp, max_irqs);
-	bnxt_set_dflt_rings(bp);
+	rc = bnxt_set_dflt_rings(bp);
+	if (rc) {
+		netdev_err(bp->dev, "Not enough rings available.\n");
+		rc = -ENOMEM;
+		goto init_err;
+	}
 
 	/* Default RSS hash cfg. */
 	bp->rss_hash_cfg = VNIC_RSS_CFG_REQ_HASH_TYPE_IPV4 |

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -950,6 +950,7 @@ struct bnxt {
 	#define BNXT_FLAG_ROCEV2_CAP	0x10000
 	#define BNXT_FLAG_ROCE_CAP	(BNXT_FLAG_ROCEV1_CAP |	\
 					 BNXT_FLAG_ROCEV2_CAP)
+	#define BNXT_FLAG_NO_AGG_RINGS	0x20000
 	#define BNXT_FLAG_CHIP_NITRO_A0	0x1000000
 
 	#define BNXT_FLAG_ALL_CONFIG_FEATS (BNXT_FLAG_TPA |		\