Kernel 4.1 : uart_register_driver return -ENOMEM

[Micka]

HI,

I'm having an issue, I need 5 uart and in the kernel log, I can see
that there is no room left for the fifth one ! the function
uart_register_driver return -ENOMEM

There is a comment about this case :

/*
 * Maybe we should be using a slab cache for this, especially if
* we have a large number of ports to handle.
  */

Do you know how can I fix that ? is it possible ?