Re: [PATCH 05/14] media: add a V4L2 OF parser

[Hans Verkuil <hverkuil@xs4all.nl>]

On Tue 9 October 2012 12:34:48 Sylwester Nawrocki wrote:
> Hi Guennadi,
> 
> On 10/08/2012 11:40 AM, Guennadi Liakhovetski wrote:
> > On Fri, 5 Oct 2012, Sylwester Nawrocki wrote:
> >> I would really like to see more than one user until we add any core code.
> >> No that it couldn't be changed afterwards, but it would be nice to ensure 
> >> the concepts are right and proven in real life.
> > 
> > Unfortunately I don't have any more systems on which I could easily enough 
> > try this. I've got a beagleboard with a camera, but I don't think I'm a 
> > particularly good candidate for implementing DT support for OMAP3 camera 
> > drivers;-) Apart from that I've only got soc-camera based systems, of 
> > which none are _really_ DT-ready... At best I could try an i.MX31 based 
> > board, but that doesn't have a very well developed .dts and that would be 
> > soc-camera too anyway.
> 
> I certainly wouldn't expect you would do all the job. I mean it would be good
> to possibly have some other developers adding device tree support based on that 
> new bindings and new infrastructure related to them. 
> 
> There have been recently some progress in device tree support for Exynos SoCs,
> including common clock framework support and we hope to add FDT support to the 
> Samsung SoC camera devices during this kernel cycle, based on the newly designed 
> media bindings. This is going to be a second attempt, after our initial RFC from 
> May [1]. It would still be SoC specific implementation, but not soc-camera based.
>  
> I wasn't a big fan of this asynchronous sub-devices probing, but it now seems
> to be a most complete solution to me. I think it just need to be done right
> at the v4l2-core so individual drivers don't get complicated too much.

After investigating this some more I think I agree with that. There are some
things where we should probably ask for advice from the i2c subsystem devs,
I'm thinking of putting the driver back into the deferred-probe state in
particular.

Creating v4l2-core support for this is crucial as it is quite complex and
without core support this is going to be a nightmare for drivers.

Regards,

	Hans