RE: Purpose of .init and .release methods in soc_camera framework

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Hi Guennadi,

> -----Original Message-----
> From: Guennadi Liakhovetski [mailto:g.liakhovetski@xxxxxx]
> Sent: Wednesday, January 11, 2012 5:18 PM
> To: Bhupesh SHARMA
> Cc: linux-media@xxxxxxxxxxxxxxx
> Subject: Re: Purpose of .init and .release methods in soc_camera
> framework
> 
> Hi Bhupesh
> 
> On Wed, 11 Jan 2012, Bhupesh SHARMA wrote:
> 
> > Hi Guennadi,
> >
> > I was reading the latest soc_camera framework documentation (see
> [1]).
> > I can see on line 71 to 73 the following text:
> >
> > " .add and .remove methods are called when a sensor is attached to or
> detached
> >  from the host, apart from performing host-internal tasks they shall
> also call
> >  sensor driver's .init and .release methods respectively."
> >
> > Now, I was puzzled on seeing that none of the soc_camera bridge
> drivers (
> > like PXA and SH Mobile) call the sensor's .init and .release from
> their
> > .add and .remove methods respectively.
> 
> .init() and .release() methods were a part of the soc-camera client
> API.
> It has been removed with the migration to the v4l2-subdev API.

Ok. So, can the documentation be updated to reflect the same.

> > Also I cannot trace these calls in soc_camera.c layer
> >
> > Actually, I am working on a camera sensor that requires certain
> > patches to be written to it before it can start working:
> >
> > - Now, if I write these patches in the _probe_ of the sensor driver
> (similar
> > to the ST VS6624 driver here : [2]), my sensor can work well for the
> 1st run
> > of the user-space application. But, if I launch the application again
> the patches
> > need to be written to the sensor again as I have implemented an 'icl-
> >power' routine
> > which basically turns ON and OFF the sensor by toggling its CE (chip
> enable pin).
> >
> > - As the soc_camera layer provides no explicit call to the camera
> sensor driver
> > when an _open_ is invoked from the userland, when and how should I
> write the
> > patch registers.
> >
> > I can only think of using the .init routine to initialize the sensor
> patch registers
> > in such a case.
> 
> Why don't you perform that initialisation in your .power() method?

You mean in the icl->power method?

Regards,
Bhupesh



> > Please share your views on the same.
> >
> > [1] http://lxr.free-
> electrons.com/source/Documentation/video4linux/soc-camera.txt
> > [2] http://www.spinics.net/lists/linux-media/msg37805.html
> >
> >
> > Regards,
> > Bhupesh
> 
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
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