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

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Message-ID: <20091215210514.GO24406@elf.ucw.cz>
Date:	Tue, 15 Dec 2009 22:05:14 +0100
From:	Pavel Machek <pavel@....cz>
To:	Jon Smirl <jonsmirl@...il.com>
Cc:	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Krzysztof Halasa <khc@...waw.pl>,
	hermann pitton <hermann-pitton@...or.de>,
	Christoph Bartelmus <lirc@...telmus.de>, awalls@...ix.net,
	j@...nau.net, jarod@...hat.com, jarod@...sonet.com,
	kraxel@...hat.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	superm1@...ntu.com
Subject: Re: [RFC] What are the goals for the architecture of an in-kernel
 IR system?

On Tue 2009-12-15 15:45:14, Jon Smirl wrote:
> On Tue, Dec 15, 2009 at 3:33 PM, Pavel Machek <pavel@....cz> wrote:
> > On Tue 2009-12-15 15:29:51, Jon Smirl wrote:
> >> On Tue, Dec 15, 2009 at 3:19 PM, Pavel Machek <pavel@....cz> wrote:
> >> > On Tue 2009-12-15 15:14:02, Jon Smirl wrote:
> >> >> On Tue, Dec 15, 2009 at 2:58 PM, Pavel Machek <pavel@....cz> wrote:
> >> >> > Hi!
> >> >> >
> >> >> >>       (11) if none is against renaming IR as RC, I'll do it on a next patch;
> >> >> >
> >> >> > Call it irc -- infrared remote control. Bluetooth remote controls will
> >> >> > have very different characteristics.
> >> >>
> >> >> How are they different after the scancode is extracted from the
> >> >> network packet? The scancode still needs to be passed to the input
> >> >> system, go through a keymap, and end up on an evdev device.
> >> >>
> >> >> I would expect the code for extracting the scancode to live in the
> >> >> networking stack, but after it is recovered the networking code would
> >> >> use the same API as IR to submit it to input.
> >> >
> >> > For one thing,  bluetooth (etc) has concept of devices (and reliable
> >> > transfer). If you have two same bluetooth remotes, you can tell them
> >> > apart, unlike IR.
> >>
> >> IR has the same concept of devices. That's what those codes you enter
> >> into a universal remote do - they set the device.
> >
> > They set the device _model_.
> >
> >> There are three classes of remotes..
> >> Fixed function - the device is hardwired
> >> Universal - you can change the device
> >> Multi-function - a universal that can be multiple devices - TV, cable,
> >> audio, etc
> >>
> >> If you set two Bluetooth remotes both to the same device you can't
> >> tell them apart either.
> >
> > Untrue. Like ethernets and wifis, bluetooth devices have unique
> > addresses. Communication is bidirectional.
> 
> I agree with that, but the 802.15.4 remote control software I've
> worked with ignores the MAC address. You set your remote to send codes
> for a specific device.  The mac address of the remote is ignored so
> that any remote can control the device.  You don't need to pair
> 802.15.4 remotes like Bluetooth devices need to be paired.
> 
> I haven't played around with a Bluetooth remote. Nothing I own can
> send the signals.  How can a Bluetooth remote control multiple devices
> in the same room if it needs to be paired?

I'd guess that bluetooth remote would be very similar to bluetooth
keyboard, and present itself in a very similar way.

I still believe infrared is different -- it is essentially light with
very little protocol above. 
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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