[linux-dvb] Re: backwards compatability -was- actual cvs broken?

Edgar Toernig froese at gmx.de
Thu Nov 3 05:34:31 CET 2005

Philip Prindeville wrote:
> Hmmm...   I personally have little use for the video functionality
> that a lot of DVB cards come with...

> Who actually uses the video capture logic?

I do.  In fact, I've bought the card only because it has an additional
(S-)Video-In connector for my game console (or vhs-recorder).

> I've always wondered...   On a multi-function card, does the driver
> have to handle all aspects of that functionality?  Or can you have
> separate, stand-alone drivers that each handle one type of
> functionality, without them having to be aware of each other
> or interact with each other?

Speaking about the BT878 based cards, the connection is already
pretty loose.  The BT878 has two functional blocks - video capture
and audio capture which show up as two different PCI devices.
The bttv driver handles the video capture part and works fine
without the dvb-driver.  The DVB "receiver" is connected to the
audio part.  Unfortunately, the DVB receiver usually needs the I2C
bus and some GPIO pins which are both part of the "video"-function
of the BT878.  So the DVB driver has to contact the bttv driver
whenever it wants access to these pins.

It should be possible to create a dummy bttv driver that only
supplies GPIO and I2C access.  This dummy driver could even be
part of the dvb-bt878 driver.  (I may be wrong but wasn't the
first version of the dvb-bt878 driver like that?)  But you
have to find someone who's willing spends some hours of work
to do that :-)  I wouldn't - it's unsatisfying to invest a
lot of work just to "remove" functionality.

Ciao, ET.

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