linux-kernel - Re: [RFC v2] Another approach to IR

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Date:	Wed, 02 Dec 2009 18:54:20 -0200
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Jon Smirl <jonsmirl@...il.com>
CC:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Devin Heitmueller <dheitmueller@...nellabs.com>,
	Maxim Levitsky <maximlevitsky@...il.com>, awalls@...ix.net,
	j@...nau.net, jarod@...hat.com, jarod@...sonet.com, khc@...waw.pl,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, lirc-list@...ts.sourceforge.net,
	superm1@...ntu.com, Christoph Bartelmus <lirc@...telmus.de>
Subject: Re: [RFC v2] Another approach to IR

Jon Smirl wrote:
> Some major use cases:
> using IR as a keyboard replacement, controlling X and apps with it in
> via mouse and keyboard emulation.
> using IR to control a headless embedded device possibly running
> multiple apps - like audio and home automation (my app)
> IR during boot when it is the only input device the box has.
> multifunction remote controlling several apps
> using several different remotes to control a single app

I think you reasonably described the major usecases.

>>> If everyone hates configfs the same mapping can be done via the set
>>> keys IOCTL and making changes to the user space apps like loadkeys.
>>>
>> It is not the hate of configfs per se, but rather concern that configfs
>> takes too much resources and is not normally enabled.
> 
> It adds about 35K on 64b x86. 30K on 32b powerpc. If it gets turned on
> by default other subsystems might start using it too. I work on an
> embedded system. These arguments about non-swapable vs swapable are
> pointless. Embedded systems don't have swap devices.

> Of course config can be eliminated by modifying the setkeys IOCTL and
> user space tools. It will require some more mods to input to allow
> multiple maps monitoring the input stream and splitting them onto
> multiple evdev devices. This is an equally valid way of building the
> maps.
> 
> The code I posted is just demo code. It is clearly not in shape to be
> merged. Its purpose was to spark a design discussion around creating a
> good long-term architecture for IR.

Unfortunately, afaik, most distros don't enable configfs yet. I have to
manually compile my kernel when I need some useful stuff there.

I agree with Dmitry: IR is probably not enough to have this enabled by
default on distros. I prefer a more traditional approach like ioctls 
(and/or sysfs) instead of configfs.

Cheers,
Mauro.
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