linux-kernel - Re: [RFC] What are the goals for the architecture of an in-kernel IR system?

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Message-ID: <9e4733910911281410i75bf19b7xa4dfd6ad1dc1b748@mail.gmail.com>
Date:	Sat, 28 Nov 2009 17:10:30 -0500
From:	Jon Smirl <jonsmirl@...il.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	Christoph Bartelmus <lirc@...telmus.de>, khc@...waw.pl,
	awalls@...ix.net, dmitry.torokhov@...il.com, j@...nau.net,
	jarod@...hat.com, jarod@...sonet.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	maximlevitsky@...il.com, mchehab@...hat.com, superm1@...ntu.com
Subject: Re: [RFC] What are the goals for the architecture of an in-kernel IR 
	system?

On Sat, Nov 28, 2009 at 4:46 PM, Stefan Richter
<stefanr@...6.in-berlin.de> wrote:
> Jon Smirl wrote:
>> On Sat, Nov 28, 2009 at 3:29 PM, Stefan Richter
>> <stefanr@...6.in-berlin.de> wrote:
>>> Jon Smirl wrote:
>>>> We have one IR receiver device and multiple remotes. How does the
>>>> input system know how many devices to create corresponding to how many
>>>> remotes you have?
>>> If several remotes are to be used on the same receiver, then they
>>> necessarily need to generate different scancodes, don't they?  Otherwise
>                                          ^^^^^^^^^
> I referred to scancodes, not keycodes.
>
>>> the input driver wouldn't be able to route their events to the
>>> respective subdevice.  But if they do generate different scancodes,
>>> there is no need to create subdevices just for EVIOCSKEYCODE's sake. (It
>>> might still be desirable to have subdevices for other reasons perhaps.)
>>
>> Multiple remotes will have duplicate buttons (1, 2 ,3, power, mute,
>> etc) these should get mapped into the standard keycodes. You need to
>> devices to key things straight.
>>
>> Push button 1 on Remote A. That should generate a KP_1 on the evdev
>> interface for that remote.
>> Push button 1 on Remote B. That should generate a KP_1 on the evdev
>> interface for that remote.
>>
>> Scenario for this - a mutifunction remote that is controlling two
>> different devices/apps. In one mode the 1 might be a channel number,
>> in the other mode it might be a telephone number.
>>
>> The user may chose to make button 1 on both remote A/B map to KP_1 on
>> a single interface.
>>
>> Scenario for this - I want to use two different remotes to control a
>> single device.
>>
>> ---------------------
>>
>> I handled that in configds like this:
>> /configfs - mount the basic configfs
>> /configfs/remotes (created by loading IR support)
>> mkdir /configfs/remotes/remote_A  - this causes the input subdevice to
>> be created, the name of it appears in the created directory.
> [...]
>
> I'm lost.  If there are two remotes sending to a single receiver, and
> their sets of scancodes do not overlap, then all is fine.  You can map
> either set of scancodes to keycodes independently.  But if their ranges

You can do this, but now the events from both remotes are occurring on
a single evdev device. If I assign Remote_A_1 to KP_1 what am I going
to assign to Remote_B_1?

> of scancodes do overlap, then even the creation of subdevices does not
> help --- the driver has no way to tell which of the remotes sent the
> signal in order to select the corresponding input subdevice, does it?

The scancodes are always unique even among different remotes.

I have three apps: mythtv, voip and home automation.  How can I use a
remote(s) to control these three apps? The concept of keyboard focus
doesn't map very well to remote controls.

My idea was to create an evdev device for each app:
mythtv - Remote_A_1 mapped KP_1, etc
voip -  Remote_B_1 mapped KP_1, etc
home automation - etc

Note that there probably aren't really three remotes (A,B,C), it a
multi-function remote. Picking a different context on a multi-function
remote doesn't generate an event.




> --
> Stefan Richter
> -=====-==--= =-== ===--
> http://arcgraph.de/sr/
>



-- 
Jon Smirl
jonsmirl@...il.com
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