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: <4B1E5BDF.7010202@redhat.com>
Date:	Tue, 08 Dec 2009 11:59:59 -0200
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Jon Smirl <jonsmirl@...il.com>
CC:	Andy Walls <awalls@...ix.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jarod Wilson <jarod@...sonet.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

Jon Smirl wrote:
> On Tue, Dec 8, 2009 at 8:30 AM, Mauro Carvalho Chehab
> <mchehab@...hat.com> wrote:
>> Andy Walls 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.)
>> You'll be distinguishing the protocol, not the remote. If I understood
>> Dmitry's question, he is asking if you can distinguish between two different
>> remotes that may, for example, be using both RC-5 or both RC-6 or one RC-5
>> and another RC-6.
> 
> RC-5 and RC-6 both contain an address field.  My opinion is that
> different addresses represent different devices and in general they
> should appear on an input devices per address.

The same IR can produce two different addresses. The IR bundled with my satellite
STB produces two different codes, depending if you previously pressed <TV> or <SAT>
key (in fact, I think it can even produce different protocols for TV, as it can
be configured to work with different TV sets).

> However, I prefer a different scheme for splitting the signals apart.
> Load separate maps containing scancodes for each address. When the IR
> signals come in they are matched against the maps and a keycode is
> generated when a match is found. Now there is no need to distinguish
> between the remotes. It doesn't matter which remote generated the
> signal.
> 
> scancode RC5/12/1 - protocol, address, command tuplet. Map this to
> KP_1 on interface 1.
> scancode RC5/7/1 - protocol, address, command tuplet. Map this to KP_1
> on interface 2.
> 
> Using the maps to split the commands out also fixes the problem with
> Sony remotes which use multiple protocols to control a single device.
> scancode Sony12/12/1 - protocol, address, command tuplet. Map this to
> power_on on interface 1.
> scancode Sony15/12/1 - protocol, address, command tuplet. Map this to
> KP_1 on interface 1.
> 

I agree.

Cheers,
Mauro.
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