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

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Message-ID: <9e4733910912080452p42efa794mb7fd608fa4fbad7c@mail.gmail.com>
Date:	Tue, 8 Dec 2009 07:52:02 -0500
From:	Jon Smirl <jonsmirl@...il.com>
To:	Andy Walls <awalls@...ix.net>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jarod Wilson <jarod@...sonet.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Krzysztof Halasa <khc@...waw.pl>,
	Christoph Bartelmus <lirc@...telmus.de>, j@...nau.net,
	jarod@...hat.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	superm1@...ntu.com
Subject: Re: [RFC] Should we create a raw input interface for IR's ? - Was: 
	Re: [PATCH 1/3 v2] lirc core device driver infrastructure

On Tue, Dec 8, 2009 at 7:35 AM, Andy Walls <awalls@...ix.net> wrote:
> On Mon, 2009-12-07 at 20:22 -0800, Dmitry Torokhov wrote:
>> On Mon, Dec 07, 2009 at 09:42:22PM -0500, Andy Walls wrote:
>
>> > So I'll whip up an RC-6 Mode 6A decoder for cx23885-input.c before the
>> > end of the month.
>> >
>> > I can setup the CX2388[58] hardware to look for both RC-5 and RC-6 with
>> > a common set of parameters, so I may be able to set up the decoders to
>> > handle decoding from two different remote types at once.  The HVR boards
>> > can ship with either type of remote AFAIK.
>> >
>> > I wonder if I can flip the keytables on the fly or if I have to create
>> > two different input devices?
>> >
>>
>> Can you distinguish between the 2 remotes (not receivers)?
>
> Yes.  RC-6 and RC-5 are different enough to distinguish between the two.
> (Honestly I could pile on more protocols that have similar pulse time
> periods, but that's complexity for no good reason and I don't know of a
> vendor that bundles 3 types of remotes per TV card.)
>
>
>>  Like I said,
>> I think the preferred way is to represent every remote that can be
>> distinguished from each other as a separate input device.
>
> OK.  With RC-5, NEC, and RC-6 at least there is also an address or
> system byte or word to distingish different remotes.  However creating
> multiple input devices on the fly for detected remotes would be madness
> - especially with a decoding error in the address bits.

I agree that creating devices on the fly has problems. Another
solution is to create one device for each map that is loaded. There
would be a couple built-in maps for bundled remotes - each would
create a device. Then the user could load more maps with each map
creating a device.

Incoming scancodes are matched against all of the loaded maps and a
keycode event is generated if a match occurs.

This illustrates why there should an EV_IR event which communicates
scancodes, without this event you can't see the scancodes that don't
match a map entry. A scancode would be first matched against the map,
then if there as no match an EV_IR event would be reported.


>
> Any one vendor usually picks one address for their bundled remote.
> Hauppaugue uses address 0x1e for it's RC-5 remotes AFAICT.
>
>
>
>>  Applications
>> expect to query device capabilities and expect them to stay somewhat
>> stable (we do support keymap change but I don't think anyone expectes
>> flip-flopping).
>
> OK.
>
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-- 
Jon Smirl
jonsmirl@...il.com
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