On Thu, Dec 6, 2012 at 8:31 PM, Alan Cox [off-list ref] wrote:

Almost none of the platforms using the serial driver even have ACPI so
this seems to be an obfuscation of a simple numbering system for a
subsystem specific set of definitions that may or may not fit in future.

OK so we need to get away from using the ACPI numbering scheme.
What about we define something in the <linux/tty.h> file instead
and delete the paragraph from the documentation saying it is related
to ACPI? (Will try this next.)

Yours,
Linus Walleij