[linux-dvb] Re: CX88 i2c issue w/ DVB tuners

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Sunday 12 Sep 2004 17:43, Johannes Stezenbach wrote:
> Holger Waechtler wrote:
> > Johannes Stezenbach wrote:
> > >Autoprobing isn't braindead.
> > >
> > >Braindead is that chip vendors omit the device id registers one
> > >needs to do autoprobing _right_. (It's Philips' fault that they
> > >didn't include device ids in the I2C spec.)
> >
> > The i2c protocol was never specified to be flexible, it does a very
> > special task and it does it quite well. Ok, i2c has it's quirks, but
> > that's not our problem right now, our problem is the linux i2c
> > infrastructure implementation by people who misunderstood the reality.
>
> Maybe you live in a different reality than I do ;-/
>
> I've seen the source of [name deleted]'s STB software, which has
> absolutely nothing to do with Linux. And guess what? They do
> device probing, too. Because in real life one piece of software
> has to run on a multitude of hardware revisions.
>
> I can't wait until [name deleted] tells you that the new
> XY frontend is cheaper that Samsung's, and could you not add
> device probing to your USB thingy firmware.
>
> The only thing that is "broken" about kernel I2C autoprobing is
> that it is too simple. But hey, it worked for all those years ;-)
>
> Now, for those cases where the simple autoprobing indeed cannot
> be made to work, the addition of a NOPROBE flag and doing more
> sophisticated probing seems like a straight forward thing to me.

Oh aye, we'll always have to do probing. However, the problems we're having 
come from the i2c core probing for every single random i2c device that 
happens to have a registered driver loaded. I bet [name deleted]'s STB 
software only probes for i2c devices that they know their device might see. 
No problems with *that* - it can fix any clashes itself, as it knows what it 
expects.

As for the changes Holger suggests w.r.t frontend libraries, they're aimed at 
cleaning up the frontend code and making it more flexible. Something which 
I've wanted to look into for some time.