Em Tue, 11 Dec 2012 22:59:06 +0200 Antti Palosaari <crope@xxxxxx> escreveu: > On 12/11/2012 10:51 PM, Frank Schäfer wrote: > > Am 10.12.2012 21:48, schrieb Antti Palosaari: > >> On 12/10/2012 09:24 PM, Frank Schäfer wrote: > >>> Am 10.12.2012 18:57, schrieb Antti Palosaari: > >>>> On 12/10/2012 06:13 PM, Devin Heitmueller wrote: > >>>>> On Mon, Dec 10, 2012 at 11:01 AM, Frank Schäfer > >>>>>> Adding a new property to the RC profile certainly seems to be the > >>>>>> cleanest solution. > >>>>>> Do all protocols have paritiy checking ? Otherwise we could add a new > >>>>>> type RC_TYPE_NEC_NO_PARITY. > >>>>>> OTOH, introducing a new bitfield in struct rc_map might be usefull > >>>>>> for > >>>>>> other flags, too, in the future... > >>>>> > >>>>> It's probably also worth mentioning that in that mode the device > >>>>> reports four bytes, not two. I guess perhaps if parity is ignored it > >>>>> reports the data in some other format? You will probably have to do > >>>>> some experimentation there. > > > > ... > > > >>>> > >>>> Uh, current em28xx NEC implementation is locked to traditional 16 bit > >>>> NEC, where is hw checksum used. > >>>> > >>>> Implementation should be changed to more general to support 24 and 32 > >>>> bit NEC too. There is multiple drivers doing already that, for example > >>>> AF9015. > >>>> > >>> > >>> Hmm... are there and documents (, links, books, ...) where I can learn > >>> more about all those RC protocols ? > >> > >> Specification comes here: > >> NEC send always 32 bit, 4 bytes. There is 3 different "sub" protocols: > >> > >> 1) 16bit NEC standard, 1 byte address code, 1 byte key code > >> full 4 byte code: AA BB CC DD > >> where: > >> AA = address code > >> BB = ~address code > >> CC = key code > >> DD = ~key code > >> > >> checksum: > >> AA + BB = 0xff > >> CC + DD = 0xff > >> > >> 2) 24bit NEC extended, 2 byte address code, 1 byte key code > >> full 4 byte code: AA BB CC DD > >> where: > >> AA = address code (MSB) > >> BB = address code (LSB) > >> CC = key code > >> DD = ~key code > >> > >> 3) 32bit NEC full, 4 byte key code > >> full 4 byte code: AA BB CC DD > >> where: > >> AA = > >> BB = > >> CC = > >> DD = > >> > >> I am not sure if there is separate parts for address and key code in > >> case of 32bit NEC. See some existing remote keytables if there is any > >> such table. It is very rare protocol. 1) and 2) are much more common. > >> > > > > Many thanks. > > So the problem is, that we have only a single RC_TYPE for all 3 protocol > > variants and need a method to distinguish between them, right ? This is not actually needed, as it is very easy to distinguish them when doing the table lookups. Take a look at v4l-utils, at /utils/keytable/rc_keymaps: A 16-bits NEC table: # table kworld_315u, type: NEC 0x6143 KEY_POWER 0x6101 KEY_VIDEO ... A 24-bits NEC table: # table pixelview_002t, type: NEC 0x866b13 KEY_MUTE 0x866b12 KEY_POWER2 ... A 32-bits NEC table: # table tivo, type: NEC 0xa10c900f KEY_MEDIA 0xa10c0807 KEY_POWER2 ... If you see there, there's no way for the Kernel to handle it wrong, as there's an implicit rule when dealing with "extended NEC" protocols: Being the IR code being given by: AA BB CC DD On a 24-bit NEC table: AA is always different than ~BB, otherwise, it would be a 16-bit NEC. On a 32-bit NEC table: CC is always different than ~DD, otherwise, it would be a 24-bit NEC. > Yes, that is. I have said it "million" times I would like to see that > implemented as a one single 4 byte NEC, but it is currently what it is. The hard thing is that, if this is changed upstream, existing tools/keytables will break. So, regressions will be introduced. > What I understand David Härdeman has done some work toward that too, but > it is not ready. One alternative would be to add some compatibility code at the table read function that would convert a 16 bits or 24 bits NEC keycode table into a 32 bits one, but doing it right can be a problem. > See current af9015 driver as example how driver makes decision which > variant of NEC is used. You will need something similar. Read all 4 NEC > bytes from the hardware and then use driver to make decision which > variant it is. I am quite sure em28xx hardware supports reading all 4 > bytes, but if not, you will need to do some other tricks. > > regards > Antti > Regards, Mauro -- 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
