Re: [RFC PATCH 0/5] Matrix and Motion Detection support

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

Hi Hans,

On 07/08/2013 09:22 AM, Hans Verkuil wrote:
> On Sun July 7 2013 23:50:30 Sylwester Nawrocki wrote:
>> On 06/28/2013 02:27 PM, Hans Verkuil wrote:
>>> This patch series adds support for matrices and motion detection and
>>> converts the solo6x10 driver to use these new APIs.
>>>
>>> See the RFCv2 for details on the motion detection API:
>>>
>>> http://www.mail-archive.com/linux-media@vger.kernel.org/msg62085.html
>>>
>>> And this RFC for details on the matrix API (which superseeds the v4l2_md_blocks
>>> in the RFC above):
>>>
>>> http://permalink.gmane.org/gmane.linux.drivers.video-input-infrastructure/65195
>>>
>>> I have tested this with the solo card, both global motion detection and
>>> regional motion detection, and it works well.
>>>
>>> There is no documentation for the new APIs yet (other than the RFCs). I would
>>> like to know what others think of this proposal before I start work on the
>>> DocBook documentation.
>>
>> These 3 ioctls look pretty generic and will likely allow us to handle wide
>> range of functionalities, similarly to what the controls framework does 
>> today.
>>
>> What I don't like in the current trend of the V4L2 API development 
>> though is
>> that we have seemingly separate APIs for configuring integers, rectangles,
>> matrices, etc. And interactions between those APIs sometimes happen to be
>> not well defined.
>>
>> I'm not opposed to having this matrix API, but I would _much_ more like to
>> see it as a starting point of a more powerful API, that would allow to 
>> model
>> dependencies between parameters being configured and the objects more
>> explicitly and freely (e.g. case of the per buffer controls), that would
>> allow to pass a list of commands to the hardware for atomic 
>> re-configurations,
>> that would allow to create hardware configuration contexts, etc., etc.
>>
>> But it's all song of future, requires lots of effort, founding and takes
>> engineers with significant experience.
>>
>> As it likely won't happen soon I guess we can proceed with the matrix API
>> for now.
> 
> Do you attend the LPC in New Orleans? I would like to discuss this further,
> but it is easier to do so face-to-face with a whiteboard. Alternatively, we
> could set up a brainstorm session somewhere. This discussion keeps cropping
> up time and again, perhaps we should start to do something about it :-)

My apologies for the delay. I'm not planning to attend LPC, certainly
discussing this in person sounds like a good idea. I will be most likely
attending ELCE in Edinburg though, perhaps we could have some meeting
organized there, if there are other persons interested in that.

--
Regards,
Sylwester