On Mon, 2009-12-07 at 13:19 -0500, Jarod Wilson wrote:

On Nov 26, 2009, at 2:43 PM, Andy Walls wrote:

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On Thu, 2009-11-26 at 12:05 -0200, Mauro Carvalho Chehab wrote:

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Krzysztof Halasa wrote:

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Andy Walls [off-list ref] writes:

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I would also note that RC-6 Mode 6A, used by most MCE remotes, was
developed by Philips, but Microsoft has some sort of licensing interest
in it and it is almost surely encumbered somwhow:

I don't know about legal problems in some countries but from the
technical POV handling the protocol in the kernel is more efficient
or (/and) simpler.

A software licensing from Microsoft won't apply to Linux kernel, so I'm
assuming that you're referring to some patent that they could be filled
about RC6 mode 6A.

I don't know if is there any US patent pending about it (AFAIK, only US
accepts software patents), but there are some prior-art for IR key
decoding. So, I don't see what "innovation" RC6 would be adding. 
If it is some new way to transmit waves, the patent issues
aren't related to software, and the device manufacturer had already handled
it when they made their devices.

If it is just a new keytable, this issue 
could be easily solved by loading the keytable via userspace.

Also, assuming that you can use the driver only with a hardware that comes
with a licensed software, the user has already the license for using it.

Do you have any details on what patents they are claiming?

The US Philips RC-6 patent is US Patent 5,877,702

http://www.google.com/patents?vid=USPAT5877702

Click on download PDF to get a copy of the whole patent.

I am not a lawyer.  Philips claims' all appear to tie to a transmitter
or receiver as part of a system, but most of the claims are about
information and bit positions and lengths.

...

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IMO, given

a. the dearth of public information about RC-6, indicating someone
thinks it's their trade secret or intellectual property

b. Microsoft claiming to license something related to the MCE remote
protocols (which are obviously RC-6 Mode 6A),

c. my inability to draw a "clear, bright line" that RC-6 Mode 6A
encoding and decoding, as needed by MCE remotes, implemented in software
doesn't violate anyone's government granted rights to exclusivity.

I think it's much better to implement software RC-6 Mode 6A encoding and
decoding in user space, doing only the minimum needed to get the
hardware setup and going in the kernel.  

Encoding/decoding of RC-6 by microcontrollers with firmware doesn't
worry me. 


Maybe I'm being too conservative here, but I have a personal interest in
keeping Linux free and unencumbered even in the US which, I cannot deny,
has a patent system that is screwed up.

So I had one of the people who does all the license and patent audits
for Fedora packages look at the Philips patent on RC-6. He's 100%
positive that the patent *only* covers hardware, there should be no
problem whatsoever writing a software decoder for RC-6.

OK.  Thanks for having some professionals take a look.  (I'm assuming
that's the only patent.)

So I'll whip up an RC-6 Mode 6A decoder for cx23885-input.c before the
end of the month.

I can setup the CX2388[58] hardware to look for both RC-5 and RC-6 with
a common set of parameters, so I may be able to set up the decoders to
handle decoding from two different remote types at once.  The HVR boards
can ship with either type of remote AFAIK.

I wonder if I can flip the keytables on the fly or if I have to create
two different input devices?

Regards,
Andy