On 01/15/2014 06:25 PM, Antti Palosaari wrote:
> On 14.01.2014 03:44, Antti Palosaari wrote:
>> On 05.01.2014 14:13, Hans Verkuil wrote:
>>> On 12/29/2013 05:03 AM, Antti Palosaari wrote:
>>>> VIDIOC_QUERYCAP IOCTL is used to query device capabilities. Add new
>>>> capability flag to inform given device supports SDR capture.
>>>>
>>>> Cc: Hans Verkuil <hverkuil@xxxxxxxxx>
>>>> Signed-off-by: Antti Palosaari <crope@xxxxxx>
>>>> Acked-by: Hans Verkuil <hverkuil@xxxxxxxxx>
>>>> ---
>>>> include/uapi/linux/videodev2.h | 2 ++
>>>> 1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/include/uapi/linux/videodev2.h
>>>> b/include/uapi/linux/videodev2.h
>>>> index c50e449..f596b7b 100644
>>>> --- a/include/uapi/linux/videodev2.h
>>>> +++ b/include/uapi/linux/videodev2.h
>>>> @@ -267,6 +267,8 @@ struct v4l2_capability {
>>>> #define V4L2_CAP_RADIO 0x00040000 /* is a radio device */
>>>> #define V4L2_CAP_MODULATOR 0x00080000 /* has a modulator */
>>>>
>>>> +#define V4L2_CAP_SDR_CAPTURE 0x00100000 /* Is a SDR capture
>>>> device */
>>>> +
>>>> #define V4L2_CAP_READWRITE 0x01000000 /* read/write
>>>> systemcalls */
>>>> #define V4L2_CAP_ASYNCIO 0x02000000 /* async I/O */
>>>> #define V4L2_CAP_STREAMING 0x04000000 /* streaming
>>>> I/O ioctls */
>>>>
>>>
>>> This new capability needs to be documented in DocBook as well
>>> (vidioc-querycap.xml).
>>
>> It is already.
>
> There is following related flags:
>
> V4L2_CAP_TUNER
> V4L2_CAP_RADIO
> V4L2_CAP_MODULATOR
> V4L2_CAP_SDR_CAPTURE
>
> V4L2_CAP_TUNER flag is overlapping with all these and is redundant at
> least currently. Lets take a example as a radio device. There is
> V4L2_CAP_RADIO flag to say it is radio and then there is flag
> V4L2_CAP_TUNER which means signal is coming from antenna? So there could
> be radio device without V4L2_CAP_TUNER flag, for example radio over IP,
> right?
The tuner cap is important to tell the difference between a radio tuner
and a radio modulator. In addition you need this capability tell userspace
that the video capture device has a tuner. Video capture without a tuner
is quite common.
> Due to that I started thinking relation of V4L2_CAP_SDR_CAPTURE and
> V4L2_CAP_TUNER and V4L2_CAP_RADIO flags. ADC is pretty much mandatory
> element of SDR receiver (and DAC SDR transmitter). Whilst ADC is
> mandatory, RF tuner is not. So should I map V4L2_CAP_TUNER to indicate
> there is RF tuner?
I don't think so. The capabilities really tell userspace what APIs are
supported by the driver. Even though the ADC is perhaps not a 'real' tuner,
the tuner API is still used to program it.
Regards,
Hans
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