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[linux-dvb] Re: CX88 i2c issue w/ DVB tuners
Andrew de Quincey writes:
> On Friday 10 Sep 2004 11:02, John Dalgliesh wrote:
> > On Fri, 10 Sep 2004, Andrew de Quincey wrote:
> > > On Thursday 09 Sep 2004 23:41, Gerd Knorr wrote:
> > > > > Just hope there isn't a card out there with both DVB AND analogue
> > > > > tuners on it....
> > > >
> > > > class isn't a value but a bitmask, so you can actually say the card
> > > > can do both analog and digital tv ...
> > >
> > > Ah right cool. Eurgh, nasty problem waiting down the line when those
> > > cards Holger mentioned appear.
> >
> > I don't think I understand the condition you are worried about. Do you
> > mean that the card has to have two separate (i2c-addressable) tuners, one
> > for analogue and one for digital? Or would a card that has one tuner that
> > does both like <http://www.dvico.com/products_mul_hd3.html> be a worry?
> >
> > Just wondering :)
>
> If the card is marked as both analogue and digital, and happens to use one of
> the i2c addresses which several devices use, you could end up with the wrong
> i2c device associated with the wrong device - e.g. the tda9987 (analogue
> tuner) driver was being used incorrectly as the driver for the cx22702
> (digtial demodulator) because they both commonly reside at the same i2c
> address. And theres no way to detect the tda9887 more specifically.
I think before (a year or so ago) when possible improvements
of the kernel i2c driver for DVB were discussed on this list
one of the ideas was to add a type field to the i2c client.
Something like I2C_DVB_DEMOD, I2C_DVB_TUNER, I2C_ANALOG_TUNER,
I2C_ANALOG_SOUND_THINGY_GADGET, etc.
The i2c driver could then choose in the attach function what kind of
clients to accept and how to configure them.
Ralph
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