Re: [PATCH 3/6] ir-kbd-i2c: Switch to the new-style device binding model

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Hi!

Am Sonntag, den 12.04.2009, 13:37 -0400 schrieb CityK:
> Mauro Carvalho Chehab wrote:
> > On Tue, 07 Apr 2009 23:02:43 -0400
> > CityK <cityk@xxxxxxxxxx> wrote:
> >
> >   
> >> Regarding the KS003 (& KS007; the other "mystery" chip):
> >>
> >> Upon further investigation of some info from a post from last year
> >> (http://www.linuxtv.org/pipermail/linux-dvb/2008-January/022634.html),
> >> it appears that these (assuming that they are the same IC across the
> >> various MSI, Leadtek & KWorld cards; and I believe that to be true) are
> >> the "AT8PS54/S56" chip from "Feeling Technology" ... the datasheet for
> >> that part is available through a google search .... probing further (as
> >> I had never heard of FT before and so I looked them up), it looks like
> >> FT renamed and/or upgraded the chip to the "FM8PS54/S56" ... the near
> >> identical datasheet for that second version is also available:
> >> http://www.feeling-tech.com.tw/km-master/front/bin/ptdetail.phtml?Part=M1-05&Category=100018
> >>     
> >
> > From what I've investigated, several of those IR chips are micro-controllers like
> > the one you pointed. I've seen a few boards whose IR chip is not masked. On
> > those, I always went into some micro-controller datasheet.
> >
> > Those IR's with a micro-controller have some software inside it to decode one IR
> > protocol and generate scan-code sequences that can be received via GPIO or via
> > I2C, depending on the firmware content.
> >
> > The datasheet of those chips are useless, since the behaviour of the
> > device is programmed inside their ROM/EEPROM [1]. So, even being the same chip,
> > you could have two "K007" devices with different firmwares, listening on
> > different i2c addresses and eventually generating different scan-codes for the
> > same IR.
> >
> > On the other hand, for USB devices and for bttv, saa7134 and cx88, there are
> > some easy ways to monitor what i2c messages or GPIO pins are involved with IR.
> > In general, the IR received messages generated by the firmware are some header,
> > a scan code, a repeat key bit and a trailer. So, it is not hard to generate a
> > get-key routine to get the scan code and the repeat bit from the protocol.
> >
> > That's why the modern ir-kbd-i2c approach is to select the proper IR parameters
> > after binding the module, at the bridge driver. The bridge driver is the one
> > who knows what's the IR scan code of the original IR (to set it as the
> > default), and the proper get-key function. With the new i2c behaviour, the
> > bridge driver can also specify the proper i2c address for each device.
> >
> > Cheers,
> > Mauro
> >
> > [1] It doesn't seem to be practical for me to get their internal software.In
> > general, such micro-controllers block EEPROM/ROM read of the software inside.
> > If this is the case of this chip, the only remaining option to get the internal
> > software would be to cut the plastic and try to see the state of each eeprom
> > bit with the help of a good microscope. 
> > Anyway, assuming that there are some way to read the ROM content, in order to
> > see the device behavior, one should remove the chip from the board, get the
> > ROM/EEPROM content, write a disassembler for this processor, disassemble the
> > code and analyse the results. This would be a real hard work, would take a lot
> > of time, and I doubt that this would help to improve the driver, since we
> > already know how to read scan codes from those devices.
> 
> Thanks for the detailed response Mauro. I've actually been wondering
> about whether the specific "KS00x" designation/label might refer to the
> embedded firmware or to a dataline, so that thought is certainly
> consistent with your description.

Consistent with that, as from some first seen ever, the KS007 chip
remotes seem to have always more keys than the KS003 ones.

Cheers,
Hermann




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