[linux-dvb] Status on de-scrambling with Twinhan DST-CI cards

Dominique Dumont domi.dumont at free.fr
Mon Mar 28 18:50:31 CEST 2005



Hello

I'm testing Manu's work with a Twinhan DST-CI clone. Things are not
going as well as expected.

My exact setup is:
- Hercules Smart TV Satellite
- CAM SCM Viacess Red Label firmware v1.06
- TPS subscription (On Hotbird)
- Asus a7n8x deluxe mobo (Nforce2)

With a modified version of Manu's drivers and ca_zap, I've managed to
get de-scrambling working for TPS (video and 2 audio channels as the
same time).

To get this working, I had to modify ca_zap so that all ca_desc are
moved from es_stream level to program level lest the CA_PMT message
send to Twinhan's firmware is too long. Currently this program is an
ugly hack. I'm working with Manu to get a better version of ca_zap.

Unfortunately, de-scrambling always fail after some time (i.e. between
15mn and 12 hours). I still haven't a clue as why de-scrambling stops.
The failure is not completely random. The card tends to fail mostly
between 12h and 14h and 20h and 23h. 

Once de-scrambling stops, Twinhan's micro-controller loose the
communication with the CAM. Only a module re-load will get the card
working again (which trigger a reinitialisation of the card)

So far I've ruled out these possible causes for a failure:
- signal loss (different symptoms)
- change of version_number or current_next_indicator in PAT or PMT
  table: I could not find anything wrong in the PMT or PAT before a
  failure of my card

Driver and card have still some troublesome areas:
- the initialization is way too long. The driver must wait 4s before
  attempting to read something from the micro-controller. Lest
  communication with the CAM does not work.
- There's no provision for profile management between CAM and host. 
- There's no provision for MMI support (although Manu is planning this
  feature)
- There's no provision for CAM Date_enq.
- In fact there's no provision for any communication initiated by the
  CAM at application level.
- CAM hot-plug does not work: CAM communication does not resume after
  un-plugging and re-plugging the CAM. (and I still don't know what
  should Twinhan's micro-controller do when the CAM is inserted or
  removed)


Currently, work is mostly done on:
- getting a clean ca_zap (i.e ca-zap application, a C library to deal
  with encoding and decoding of table and a set of unit-test for the
  lib)
- finding out why de-scrambling stops with Viaccess and TPS

If anyone has an idea about what could be the cause of these
not-so-random failures, I'd be _really_  glad to hear from you.

As you can see, we still have a lot of problems to solve before
Twinhan card gets usable under Linux (or usable at all: this card
barely works in Windows)

Any kind of help is more than welcome.

Cheers




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