On Mon, Dec 07, 2009 at 09:42:22PM -0500, Andy Walls wrote: > On Mon, 2009-12-07 at 13:19 -0500, Jarod Wilson wrote: > > On Nov 26, 2009, at 2:43 PM, Andy Walls wrote: > > > > > On Thu, 2009-11-26 at 12:05 -0200, Mauro Carvalho Chehab wrote: > > >> Krzysztof Halasa wrote: > > >>> Andy Walls <awalls@xxxxxxxxx> writes: > > >>> > > >>>> 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. > > ... > > > 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? > Can you distinguish between the 2 remotes (not receivers)? Like I said, I think the preferred way is to represent every remote that can be distinguished from each other as a separate input device. Applications expect to query device capabilities and expect them to stay somewhat stable (we do support keymap change but I don't think anyone expectes flip-flopping). -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
