[linux-dvb] Re: Request: docs/specs for dibusb

["Henning Günther" <eq@eq.homelinux.org>]

Am Mo, den 13.09.2004 schrieb Patrick Boettcher um 23:06:
> On Mon, 13 Sep 2004, Henning Günther wrote:
> 
> > Hi,
> >
> > as I'm very interested in
> > 1) getting my Twinhan VisionPlus DVB-T device running under linux
> 
> Hi,
> 
> Today morning I did another commit for the dib3000mb. With it I was able
> to receive mpeg data. Therefore one of the channel-tuning-values (when
> using tzap, for example) has to be auto (e.g. INVERSION_AUTO instead of
> INVERSION_ON), so that the autosearch process is initiated. I will work
> this problem later.
>
I'll try it.

> > 2) learning how to write device drivers
> 
> I was starting with it this year. I would recommend to start writing a
> driver for an USB device, unless you have the specs for a pci device. USB
> devices are quite easy to reverse-engineer and easy to write in linux. For
> making the first steps in kernel programming it seems to be a good way.
> 
> > I'd like to ask if it would be possible to release the
> > specifications/documentation on which the dibusb driver is based on. I'm
> > not sure if I will understand it but it might would be a great learning
> > start-point for me. Until now I only developed some user-space software
> > in C.
> 
> DiBcom did not released specs for the dib3000mb, and won't do it, unless
> you sign a NDA. They only have a comprehensive specification, wherein
> beside of the registers, also the algorithms are documented. The only
> freely available docs are the dib3000mb-sources.
> 
After thinking a bit, that's quite logical as they don't want other
manufactors to gain from their protocol.
> The only thing they gave me, was a GPL'd linux driver. This driver was not
> implemented using the Linux DVB-API, but an own one. And they are open for
> any questions. Furthermore they provide a firmware that should work with
> all of the dibusb-devices. The firmware is HEX-format (binary).
> 
Okay, that's clear. I first thought that they just gave away
specifications.

> I extracted the i2c registers and gave them names (dib3000mb.h). In the
> original DiBcom driver the register have been passed directly, quite
> difficult to read. Additionally I compared the values to the ones I got
> from reverse engineering.
>
> The dib3000mb.[ch] files contain all information about important registers
> and their values. I collected them from the driver source DiBcom sent me.
> 
> I hope I could make things about dibusb a little bit clearer.
> 
It certainly did.

Thank you for enlightening me. I think I must look quite naive now... :)

Henning