[PATCH v4] v4l2: Add support for interpreting remaining fields in VIDIOC_ENUMINPUT struct v4l2_input

[Marek Vasut]

On 5/18/23 12:04, Dmitry V. Levin wrote:
> On Thu, May 18, 2023 at 05:59:05AM +0200, Marek Vasut wrote:
>> On 5/17/23 10:19, Dmitry V. Levin wrote:
>>> On Wed, May 17, 2023 at 01:41:11AM +0200, Marek Vasut wrote:
>>>> On 5/17/23 00:48, Dmitry V. Levin wrote:
>>>>> On Sun, May 14, 2023 at 08:53:27PM +0200, Marek Vasut wrote:
>>>>> [...]
>>>>>> @@ -787,6 +790,19 @@ print_v4l2_input(struct tcb *const tcp, const kernel_ulong_t arg)
>>>>>>     		tprint_struct_next();
>>>>>>     		PRINT_FIELD_XVAL(i, type, v4l2_input_types,
>>>>>>     				 "V4L2_INPUT_TYPE_???");
>>>>>> +		tprint_struct_next();
>>>>>> +		PRINT_FIELD_X(i, audioset);
>>>>>> +		tprint_struct_next();
>>>>>> +		PRINT_FIELD_U(i, tuner);
>>>>>
>>>>> PRINT_FIELD_XVAL(i, tuner, v4l2_tuner_types, "V4L2_TUNER_???");
>>>>
>>>> I do not understand this feedback, sorry. Can you please provide any
>>>> further details ?
>>>>
>>>> Note that the tuner field in struct v4l2_input is tuner _index_, not
>>>> tuner type, in case this is what the suggestion is about .
>>>
>>> No problem, if struct v4l2_input.tuner is indeed an index and not an
>>> enum v4l2_tuner_type, then I've just been confused by the corresponding
>>> comment in include/uapi/linux/videodev2.h
>>
>> Which comment ? Have you got a line number for example ?
> 
> $ grep -nC5 'tuner;' include/uapi/linux/videodev2.h
> 1718-struct v4l2_input {
> 1719-	__u32	     index;		/*  Which input */
> 1720-	__u8	     name[32];		/*  Label */
> 1721-	__u32	     type;		/*  Type of input */
> 1722-	__u32	     audioset;		/*  Associated audios (bitfield) */
> 1723:	__u32        tuner;             /*  enum v4l2_tuner_type */
> 1724-	v4l2_std_id  std;
> 1725-	__u32	     status;
> 1726-	__u32	     capabilities;
> 1727-	__u32	     reserved[3];
> 1728-};
> 
>> The generated kerneldocs state the 'tuner' is an index:
>> https://docs.kernel.org/userspace-api/media/v4l/vidioc-enuminput.html

It seems the comment is wrong and it crept in back in 2012 during a 
clean up. I sent a patch to fix it with further explanation, you are on CC:

[PATCH] media: videodev2.h: Fix struct v4l2_input tuner index comment