[linux-dvb] Re: How to CA support in current driver? (was: Re: Re: OSD problems investigated)

[John Williams <John.Williams@pcmsdatafit.co.uk>]

At 20:16 24/02/02 +0100, you wrote:

> > You might like to investigate the new code to read and write the CI that
> > has appeared in the latest driver versions (0.9.4 and later). It is
> > undocumented, but I suppose it is doing the same as my code was trying to
> > do. Perhaps Convergence have fixed the CI support in their firmware; if
>so,
> > then I'll be the first to throw away what I've done and use their code.
>
>I'm currently trying to use the new code, but I don't know how to do it
>right. I haven't done any DVB programming before so please be gentle with me
>if I'm doing something fundamentally wrong here ;-)
>
>If I understand correctly, I have to send the Program Number to the
>CA-Interface to start decrypting a program stream. How do I do this? The
>driver code in dvb.c just reads:


Henning,

First I should say that I haven't tried this, so anything I say about it 
might be wrong.

With the original Technotrend firmware, you have to send the program number 
to the CI in order for it to start decrypting. But the Convergence firmware 
is different: you don't need to do this. It should start decrypting as soon 
as you set the video and audio PIDs. So the CA_SEND_MSG ioctl is just not 
needed with their firmware. That's why it has no code to support it. If you 
don't see a decrypted program already with the Convergence firmware, 
something else is wrong.

The thing that was missing in the Convergence stuff was a way of reading 
the "CAM menu" (used for setting the PIN code, accessing the "goodies" menu 
or whatever). My code accessed this by ioctl calls, which has not a very 
good design. Convergence have now added some code to their driver to 
support read() and write() for the "ca" device; I suppose this gives access 
to the "CAM menu". If you want to experiment, try just opening /dev/ost/ca 
and reading from it, and see what you get.

John

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