Re: [PATCH 4/8] ispvideo: Add support for G/S/ENUM_STD ioctl

[Mauro Carvalho Chehab <mchehab@infradead.org>]

Em 27-09-2011 19:41, Laurent Pinchart escreveu:
> Hi Mauro,
> 
> On Wednesday 28 September 2011 00:31:32 Mauro Carvalho Chehab wrote:
>> Em 19-09-2011 12:31, Hiremath, Vaibhav escreveu:
>>> On Friday, September 16, 2011 6:36 PM Laurent Pinchart wrote: > >> On 
> Friday 16 September 2011 15:00:53 Ravi, Deepthy wrote:
>>>>> On Thursday, September 08, 2011 10:51 PM Laurent Pinchart wrote:
>>>>>> On Thursday 08 September 2011 15:35:22 Deepthy Ravi wrote:
>>>>>>> From: Vaibhav Hiremath <hvaibhav@ti.com>
>>>>>>>
>>>>>>> In order to support TVP5146 (for that matter any video decoder),
>>>>>>> it is important to support G/S/ENUM_STD ioctl on /dev/videoX
>>>>>>> device node.
>>>>>>
>>>>>> Why so ? Shouldn't it be queried on the subdev output pad directly ?
>>>>>
>>>>> Because standard v4l2 application for analog devices will call these
>>>>> std ioctls on the streaming device node. So it's done on /dev/video to
>>>>> make the existing apllication work.
>>>>
>>>> Existing applications can't work with the OMAP3 ISP (and similar complex
>>>> embedded devices) without userspace support anyway, either in the form
>>>> of a GStreamer element or a libv4l plugin. I still believe that analog
>>>> video standard operations should be added to the subdev pad operations
>>>> and exposed through subdev device nodes, exactly as done with formats.
>>>
>>> I completely agree with your point that, existing application will not
>>> work without setting links properly. But I believe the assumption here
>>> is, media-controller should set the links (along with pad formants) and
>>> all existing application should work as is. Isn't it?
>>
>> Yes.
>>
>>> The way it is being done currently is, set the format at the pad level
>>> which is same as analog standard resolution and use existing application
>>> for streaming...
>>
>> Yes.
>>
>>> I am ok, if we add s/g/enum_std api support at sub-dev level but this
>>> should also be supported on streaming device node.
>>
>> Agreed. Standards selection should be done at device node, just like any
>> other device.
> 
> No. Please see my reply to Vaibhav's e-mail. Standard selection should be done 
> on the subdev pads, for the exact same reason why formats and selection 
> rectangles are configured on subdev pads.

NACK. Let's not reinvent the wheel. the MC should not replace the V4L2 API.

Mauro.