diff --git a/drivers/net/ethernet/mellanox/mlx4/fw.c b/drivers/net/ethernet/mellanox/mlx4/fw.c
index 9c83bb8..4281ce0 100644
--- a/drivers/net/ethernet/mellanox/mlx4/fw.c
+++ b/drivers/net/ethernet/mellanox/mlx4/fw.c
@@ -881,11 +881,12 @@
 		((fw_ver & 0xffff0000ull) >> 16) |
 		((fw_ver & 0x0000ffffull) << 16);
 
+	MLX4_GET(lg, outbox, QUERY_FW_PPF_ID);
+	dev->caps.function = lg;
+
 	if (mlx4_is_slave(dev))
 		goto out;
 
-	MLX4_GET(lg, outbox, QUERY_FW_PPF_ID);
-	dev->caps.function = lg;
 
 	MLX4_GET(cmd_if_rev, outbox, QUERY_FW_CMD_IF_REV_OFFSET);
 	if (cmd_if_rev < MLX4_COMMAND_INTERFACE_MIN_REV ||
@@ -966,9 +967,12 @@
 	if (err)
 		return err;
 
-	/* for slaves, zero out everything except FW version */
+	/* for slaves, set pci PPF ID to invalid and zero out everything
+	 * else except FW version */
 	outbuf[0] = outbuf[1] = 0;
 	memset(&outbuf[8], 0, QUERY_FW_OUT_SIZE - 8);
+	outbuf[QUERY_FW_PPF_ID] = MLX4_INVALID_SLAVE_ID;
+
 	return 0;
 }
 
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index 6a8f002..8eadf0f1 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -534,6 +534,8 @@
 		if (((dev)->caps.port_mask[port] == MLX4_PORT_TYPE_IB) || \
 			((dev)->caps.flags & MLX4_DEV_CAP_FLAG_IBOE))
 
+#define MLX4_INVALID_SLAVE_ID	0xFF
+
 static inline int mlx4_is_master(struct mlx4_dev *dev)
 {
 	return dev->flags & MLX4_FLAG_MASTER;