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

Gary Thomas
2011-09-27T22:49:26Z

On 2011-09-27 16:31, Mauro Carvalho Chehab wrote:
> Em 19-09-2011 12:31, Hiremath, Vaibhav escreveu:
>>
>>> -----Original Message-----
>>> From: Laurent Pinchart [mailto:laurent.pinchart@ideasonboard.com]
>>> Sent: Friday, September 16, 2011 6:36 PM
>>> To: Ravi, Deepthy
>>> Cc: linux-media@vger.kernel.org; tony@atomide.com; linux@arm.linux.org.uk;
>>> linux-omap@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
>>> kernel@vger.kernel.org; mchehab@infradead.org; g.liakhovetski@gmx.de;
>>> Hiremath, Vaibhav
>>> Subject: Re: [PATCH 4/8] ispvideo: Add support for G/S/ENUM_STD ioctl
>>>
>>> Hi Deepthy,
>>>
>>> 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.
>>>
>> [Hiremath, Vaibhav] Laurent,
>>
>> 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.

So how do you handle a part like the TVP5150 that is standard agnostic?
That device can sense the standard from the input signal and sets the
result appropriately.

--
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Gary Thomas | Consulting for the
MLB Associates | Embedded world
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