Re: [RFC] Should we create a raw input interface for IR's ? - Was: Re: [PATCH 1/3 v2] lirc core device driver infrastructure

[Devin Heitmueller <dheitmueller@kernellabs.com>]

On Mon, Nov 23, 2009 at 12:05 PM, James Mastros <james@mastros.biz> wrote:
> 2009/11/23 Devin Heitmueller <dheitmueller@kernellabs.com>:
>> Just bear in mind that with the current in-kernel code, users do *not
>> * have to manually select the RC code to use if they are using the
>> default remote that shipped with the product.
> This could still happen, if LIRC checks the identifiers of the
> reciving device, and has a database that tells it mappings between
> those devices and the remote controls that shipped with them.
> However, it occours to me that the IR circumstances map pretty well to
> what happens with ps/2 and serial devices now:
>
> 1: There are a variety of drivers for serio computer-side hardware,
> each of which speaks the serio interface to the next-higher level.
> These corrospond to the drivers for IR recievers.
> 2: There's a raw serio interface, for those wishing to do strange things.
> 3: There's also a variety of things that take data, using the kernel
> serio API, and decode it into input events -- the ps2 keyboard driver,
> the basic mouse driver, the advanced mice drivers.  This is where the
> interface falls down a little bit -- the ps2 keyboard driver is the
> closest analogue to what I'm suggesting.  The ps2 keyboard driver
> creates scancode events, which map nicely to what the keyboard is
> sending -- these are, for ex, rc5 codes.  It will also produce
> key-up/key-down events, if it has a keymap loaded.  (This is the
> difference with a ps2 keyboard -- a ps2 keyboard gets a map assigned
> to it at boottime, so it works out-of-box.  This isn't really possible
> with an IR remote -- though perhaps rc5 is standarized enough, I don't
> think other protocols neccessarly are.)
>
> Userspace would have to load a keymap; those don't really belong in
> kernel code.  Of course, userspace could look at the device
> identifiers to pick a reasonable default keymap if it's not configured
> to load another, solving the out-of-box experince.

I think perhaps before we go much further into this, we may wish to
come up with a set of use cases and expected behavior.  I worry that
part of the problem here is people are thinking of how their
particular cards behave, and few people have a holistic picture of all
the possible scenarios.  Whatever implementation we come up, we should
be confident that it meets the requirements of *all* the various
hardware implementations.

I will try to draft up some requirements/use cases if people think
this would be worthwhile.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com
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