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[linux-dvb] Re: Twinhan CA
Manu Abraham writes:
> > standard En50221 packets minus header and length field plus their own
> What about the ASIC instructions ?
> > header we could also just send those. The driver would just have to
> > exchange the headers from standard En50221 to Twinhan and vice versa.
> > Or do you want to use extra ioctls like Twinhan does in their API?
> It is somewhat like this...
> The CA commands are wrapped as one chunk and treated as data to the ASIC. The
> ASIC reads in the command and does the appropriate of sending in the desired
> command to the CAM. Then there are commands to the ASIC also.
> Regarding the ioctls, if i can add an integer preceding the commands to the
> CA_GET and or CA_SET ioctls as per the standard CA interface which exists as
> of now, i can have this driver also work on the same ioctls. This would make
> the driver/interface generic.
> This integer, ie 16 bits, would be a wrapper for the commands to the ASIC. All
> the ASIC magic would be hidden in these 2 chars.
> The question is whether to have the ASIC instructions (which can be reduced to
> 2 bytes) to be known upwards or not.
> In the other case, if this is unacceptable, we have to settle down with
> individual IOCTL's for each ASIC instruction.
What would these 2 bytes be, command type and session number?
Or do we need anything else?
We could encode the command type with the normal EN50221 command headers
(3 byte tag + length field) and prepend this (or just use the "type" field,
see other mail).
I think the session number is rather specific to the
implementation or will this always be 3 for the SEND_PMT command?
Either we add this as an exra hint to the type field or we leave it
to the driver to use the correct session number for each command?
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