[vdr] Conditional access questions

[Mark Watson <linuxtv@foft.fsnet.co.uk>]

I am trying to get VDR working with a somewhat custom setup and would 
appreciate some help. 

Basically I have modified a digital STB to get a DVB stream out of it. I wrote 
a kernel driver so that it is presented to Linux as a normal DVB device. The 
frontend device is implemented by sending IR commands to the STB using LIRC 
(and a horrible userspace/kernelspace hack using named pipes and filp_open!).

The problem I have is with handling tuning and conditional access properly. I 
have to tune to the correct channel, not just the correct transponder. This 
is because the box only descrambles the current channel. Ideally I want to be 
told by VDR "tune to transponder X to listen to service Y" all in one 
request.

As a temporary hack I generated a custom channels.conf with the service id in 
place of frequency. To tune I simply tell the STB to go to the channel 
containing that service. This mostly works except I lose the ability to have 
automatically updating channels.conf. It also seems ugly.

I presume this should be done using the CA device, but I can find no 
documentation on how this works:-( Can anyone suggest anything? Has anyone 
else tried anything similar?

Thanks,

Mark