[linux-dvb] Re: backwards compatability -was- actual cvs broken?
philipp_subx at redfish-solutions.com
Thu Nov 3 07:48:41 CET 2005
Michael Krufky wrote:
> Edgar Toernig wrote:
>> 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.
> Sure it's possible, but please, don't. This would be moving
> backwards. Why write out a driver that isnt going to go away?
> It's ONE kernel. One kernel, with subsystems, that are all part of
> the same ONE KERNEL.
Which has the undesirable effect of causing changes to have a ripple effect
all through the code, rather than being neatly self-contained. Too bad
that V4L doesn't evolve independently of DVB.
More information about the linux-dvb