linux-kernel - Re: IR raw input is not sutable for input system

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Nov 2009 18:18:38 +0100
From:	Krzysztof Halasa <khc@...waw.pl>
To:	Trent Piepho <xyzzy@...akeasy.org>
Cc:	Maxim Levitsky <maximlevitsky@...il.com>,
	Jarod Wilson <jarod@...sonet.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Jarod Wilson <jarod@...hat.com>, linux-kernel@...r.kernel.org,
	Mario Limonciello <superm1@...ntu.com>,
	linux-input@...r.kernel.org, linux-media@...r.kernel.org,
	Janne Grunau <j@...nau.net>,
	Christoph Bartelmus <lirc@...telmus.de>
Subject: Re: IR raw input is not sutable for input system

Trent Piepho <xyzzy@...akeasy.org> writes:

> The signal recevied by the ir receiver contains glitches.  Depending on the
> receiver there can be quite a few.  It is also not trivial to turn the raw
> signal sent by the remote into a digital value, even if you know what to
> expect.  It takes digital signal processing techniques to turn the messy
> sequence of inaccurate mark and space lengths into a best guess at what
> digital code the remote sent.

This is of course true. Except that most receivers do that in hardware,
the receiver/demodular chip such as TSOP1838 does it.
If you receive with a phototransistor or a photodiode feeding some sort
of ADC device (not a very smart design), sure - you have to do this
yourself.

I have never heard of such receiver, though.

> One thing that could be done, unless it has changed much since I wrote it
> 10+ years ago, is to take the mark/space protocol the ir device uses and sent
> that data to lircd via the input layer.  It would be less efficient, but
> would avoid another kernel interface.  Of course the input layer to lircd
> interface would be somewhat different than other input devices, so
> it's not entirely correct to say another interface is avoided.

IOW, it would be worse, wouldn't it?
-- 
Krzysztof Halasa
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/