Keyboard drivers, polling vs. non-polling mode

[Maxim Ignatenko]

Hello,

I'm trying trying to get keyboard working in DDB on HP Chromebook 11 (ARM).
br@ said that it doesn't work there because polling mode is not implemented yet.
Where can I read about the difference between polling and non-polling
modes (and about keyboard drivers in general)?
sys/dev/kbd/kbdreg.h describes some structures and method signatures,
but I have no clue what is the expected behaviour of those methods.

My current guess is that in polling mode keyboard driver just queues
up all the input coming from keyboard and then gives it to consumer
upon request, while in non-polling mode it invokes some callback
instead of queueing. But I cannot find any documentation to confirm or
disprove that.

-- 
Best regards,
Max