bnxt_en: Reserve rings at driver open if none was reserved at probe time.

Add logic to reserve default rings at driver open time if none was
reserved during probe time.  This will happen when the PF driver did
not provision minimum rings to the VF, due to more limited resources.

Driver open will only succeed if some minimum rings can be reserved.
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

@@ -6844,6 +6844,8 @@ static void bnxt_preset_reg_win(struct bnxt *bp)
 	}
 }
 
+static int bnxt_init_dflt_ring_mode(struct bnxt *bp);
+
 static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 {
 	int rc = 0;
@@ -6851,6 +6853,12 @@ static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 	bnxt_preset_reg_win(bp);
 	netif_carrier_off(bp->dev);
 	if (irq_re_init) {
+		/* Reserve rings now if none were reserved at driver probe. */
+		rc = bnxt_init_dflt_ring_mode(bp);
+		if (rc) {
+			netdev_err(bp->dev, "Failed to reserve default rings at open\n");
+			return rc;
+		}
 		rc = bnxt_reserve_rings(bp);
 		if (rc)
 			return rc;
@@ -8600,6 +8608,29 @@ static int bnxt_set_dflt_rings(struct bnxt *bp, bool sh)
 	return rc;
 }
 
+static int bnxt_init_dflt_ring_mode(struct bnxt *bp)
+{
+	int rc;
+
+	if (bp->tx_nr_rings)
+		return 0;
+
+	rc = bnxt_set_dflt_rings(bp, true);
+	if (rc) {
+		netdev_err(bp->dev, "Not enough rings available.\n");
+		return rc;
+	}
+	rc = bnxt_init_int_mode(bp);
+	if (rc)
+		return rc;
+	bp->tx_nr_rings_per_tc = bp->tx_nr_rings;
+	if (bnxt_rfs_supported(bp) && bnxt_rfs_capable(bp)) {
+		bp->flags |= BNXT_FLAG_RFS;
+		bp->dev->features |= NETIF_F_NTUPLE;
+	}
+	return 0;
+}
+
 int bnxt_restore_pf_fw_resources(struct bnxt *bp)
 {
 	int rc;