Re: [RFCv2 PATCH 4/6] videodev2.h: add frequency band information.

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 06/19/2012 06:47 PM, Hans de Goede wrote:
> Hi,
>
> <snip long discussion about having a fixed set of bands versus
> a way to enumerate bands, including their rangelow, rangehigh
> and capabilities>
>
> Ok, you've convinced me. I agree that having a way to actually
> enumerate ranges, rather then having a fixed set of ranges, is
> better.
>
> Which brings us back many weeks to the proposal for making
> it possible to enumerate bands on radio devices. Rather
> then digging up the old mails lets start anew, I propose
> the following API for this:
>
> 1. A radio device can have multiple tuners, but only 1 can
> be active (streaming audio to the associated audio input)
> at the same time.
>
> 2. Radio device tuners are enumerated by calling G_TUNER
> with an increasing index until EINVAL gets returned
>
> 3. G_FREQUENCY will always return the frequency and index
> of the currently active tuner
>
> 4. When calling S_TUNER on a radio device, the active
> tuner will be set to the v4l2_tuner index field
>
> 5. When calling S_FREQUENCY on a radio device, the active
> tuner will be set to the v4l2_frequency tuner field
>
> 6. On a G_TUNER call on a radio device the rxsubchans,
> audmode, signal and afc v4l2_tuner fields are only
> filled on for the active tuner (as returned by
> G_FREQUENCY) for inactive tuners these fields are reported
> as 0.

p.s.

I forgot:

7. When calling VIDIOC_S_HW_FREQ_SEEK on a radio device, the active
tuner will be set to the v4l2_hw_freq_seek tuner field

8. When changing the active tuner with S_TUNER or S_HW_FREQ_SEEK,
the current frequency may be changed to fit in the range of the
new active tuner

9. For backwards compatibility reasons tuner 0 should be the tuner
with the broadest possible FM range

Regards,

Hans