Re: RFC: V4L2 API and radio devices with multiple tuners

[Antti Palosaari <crope@iki.fi>]

On 19.05.2012 21:20, Hans de Goede wrote:
> Currently the V4L2 API does not allow for radio devices with more then 1
> tuner,
> which is a bit of a historical oversight, since many radio devices have 2
> tuners/demodulators 1 for FM and one for AM. Trying to model this as 1
> tuner
> really does not work well, as they have 2 completely separate frequency
> bands
> they handle, as well as different properties (the FM part usually is stereo
> capable, the AM part is not).
>
> It is important to realize here that usually the AM/FM tuners are part
> of 1 chip, and often have only 1 frequency register which is used in
> both AM/FM modes. IOW it more or less is one tuner, but with 2 modes,
> and from a V4L2 API pov these modes are best modeled as 2 tuners.
> This is at least true for the radio-cadet card and the tea575x,
> which are the only 2 AM capable radio devices we currently know about.

For DVB API we changed just opposite direction - from multi-frontend to 
single-frontend. I think one device per one standard is good choice.

 From DVB FE change there is now some problems as a frequency limits and 
other parameters are shared between all the standards... For example 
cxd2820r demod, which is DVB-T/T2/C, says it supports even DVB-C2 as 2nd 
generation flag is derived from the DVB-T2.

regards
Antti
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