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

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Date:	Sun, 29 Nov 2009 14:01:35 -0200
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Jon Smirl <jonsmirl@...il.com>
CC:	Stefan Richter <stefanr@...6.in-berlin.de>,
	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, superm1@...ntu.com
Subject: Re: [RFC] What are the goals for the architecture of an in-kernel
 IR 	system?

Jon Smirl wrote:
> On Sat, Nov 28, 2009 at 2:45 PM, Stefan Richter
> <stefanr@...6.in-berlin.de> wrote:
>> Jon Smirl wrote:
>>> Also, how do you create the devices for each remote? You would need to
>>> create these devices before being able to do EVIOCSKEYCODE to them.
>> The input subsystem creates devices on behalf of input drivers.  (Kernel
>> drivers, that is.  Userspace drivers are per se not affected.)
> 
> 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? There is no current mechanism to do that. You need
> an input device for each remote so that you can do the EVIOCSKEYCODE
> against it. Some type of "create subdevice" IOCTL will need to be
> built.
> 
> 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.
> mkdir /configfs/remotes/remote_A/... - now build the mapping entires.
> 
> This "create subdevice" IOCTL will need to take a name so that it can
> be identified. You will probably another IOCTL to enumerate which
> subdevices belong to the root device, etc...
> 
> Keyboards don't have subdevices. There is a 1:1 mapping between the
> keyboard and the device driver.

The above struct doesn't fit for the already existing in-kernel drivers, since
you may have more than one IR driver on kernel. I have some machines here with
3 or 4 different input cards, each with their own IR hardware. How are you
supposing to associate a created Remote Controller with the corresponding driver?

With EVIOSKEYCODE, it is as simple as directing the ioctl to the corresponding
evdev interface.

Cheers,
Mauro.
> 

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