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Date: Mon, 12 May 2014 07:41:22 +0200
From: Hans Petter Selasky <hps@selasky.org>
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To: Maxim Ignatenko <gelraen.ua@gmail.com>, freebsd-hackers@freebsd.org
Subject: Re: Keyboard drivers, polling vs. non-polling mode
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On 05/12/14 00:33, Maxim Ignatenko wrote:
> 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.
>

Hi,

Maybe you get some clues from looking at /sys/dev/usb/input/ukbd.c 
regarding polling mode.

--HPS