Re: [PATCH RFC v6 07/12] v4l: add device capability flag for SDR receiver

[Antti Palosaari <crope@iki.fi>]

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@xs4all.nl>
>>> Signed-off-by: Antti Palosaari <crope@iki.fi>
>>> Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
>>> ---
>>>   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?

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?

regards
Antti

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