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Re: Discussion: How to deal with radio tuners which can tune to multiple bands


On 05/26/2012 08:22 PM, Hans Verkuil wrote:
On Sat May 26 2012 20:09:53 Hans de Goede wrote:

On 05/26/2012 06:40 PM, Hans Verkuil wrote:
On Sat May 26 2012 18:02:34 Hans de Goede wrote:

On 05/24/2012 09:12 PM, Hans de Goede wrote:

On 05/24/2012 05:00 PM, Hans Verkuil wrote:
I think / hope that covers everything we need. Suggestions ? Comments ?

Modulators. v4l2_modulator needs a band field as well. The capabilities are
already shared with v4l2_tuner, so that doesn't need to change.

Ah, yes modulators, good one, ack.

Manjunatha, since the final proposal is close to yours, and you already have
a patch for that including all the necessary documentation updates, can I ask
you to update your patch to implement this proposal?

So I've been working a bit on adding AM support to the tea575x driver using
the agreed upon API, some observations from this:

1) There is no way to get which band is currently active

Huh? Didn't G_TUNER return the current band? That's how I interpreted the
proposal. G_TUNER returns the available bands in capabilities and the current
band and its frequency range. You want to find the frequency range of another
band you call have to call S_TUNER first to select that other band, and then
G_TUNER to discover its range.

Ah, we misunderstood each other there, I thought G_TUNER would honor the band
passed in and return info on that band.

That also solves case 2. No need for an extra band in v4l2_frequency.

Right, the downside to this is that there is no way to just enumerate things
without actually changing anything. It would be nice if for example v4l2-ctl
could lists all bands including ranges as a 100% read-only operation.

Note I'm ok with the way you propose to handle things, just pointing out
one (obvious) shortcoming of doing things this way. I think it is a short coming
we can live with, but we should be aware of it.

Well, the important thing is that you know what bands are supported, and you
know because of the capabilities.

I agree.

I don't really think you have to query the
exact range of other than the current band: the band's name is already a good
indication of what the range will be, you just don't know the exact boundaries
until you switch to that band. Which I believe is perfectly reasonable.

I agree, so lets go with your proposal / my original proposal as interpreted by
you :)


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