[linux-dvb] Re: DVB-CI question

[Ralph Metzler <rjkm@metzlerbros.de>]

Andrew de Quincey writes:
 > Sure, thats what I was intending to do. However, I need to finish it first in 
 > line with these new ideas (I've kept the old code though, but that does not 
 > work as I was still debugging it).
 > 
 > > I'd like to hear Ralph's or Marcus's opinion, as they originally
 > > wrote the CI code in the av7110 firmware and driver, and I think
 > > they know a good deal more about that stuff than I do.
 > 
 > Yep, absolutely. I mean, I'm not trying to "get out" of writing the 
 > defragmentation code; I just don't see the need for it in-kernel.
 > 


AFAIR, the reason for handling the defragmentation in the firmware was
that we thought that the overhead of exchanging messages with the
kernel driver for each 128 byte packet (or whatever CI driver and
module settle on) is too much, especially when recording at the same
time. Of course one can transfer more packets at once, but then one
can also already defragment them ...

For other hardware this can of course be handled in user space.
If you keep the interfaces between layers general enough it should
also be no problem to support drivers with other interfaces (like the
av7110 cards or also the Twinhan cards with even higher level interface) with
the same code.


Ralph






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