Re: [RFC v2 3/3] dt: bindings: Add a binding for referencing EEPROM from camera sensors

[Pavel Machek <pavel@ucw.cz>]

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Hi!

> > I agree, yes. I think the only way to solve this is to have a generic
> > EEPROM API that allows the camera sensor to read data from it. If
> 
> We have one already, and it's defined in Documentation/misc-devices/eeprom .
> 
> > another vendor uses a different type of EEPROM, the sensor driver would
> > remain the same, as it only reads data from the storage behind the
> > phandle, not caring about the details.
> > 
> > Same goes for the lens driver, and after thinking about it for awhile,
> > I'd say it makes most sense to allow referencing a v4l2_subdev device
> > through a phandle from another v4l2_subdev, and then offload certain
> > commands such as V4L2_CID_FOCUS_ABSOLUTE to the device that does the
> > actual work. Opinions?
> 
> There are different kinds of lens systems and I don't think the sensor
> drivers should be aware of them. The current approach is that the lens is a
> separate sub-device --- the intent of the patchset I posted was to document
> how the information on the related lens and eeprom components is conveyed to
> the software. There's one such driver in the mainline kernel, ad5820.
> 
> Unfortunately we don't right now have a good user space interface for
> telling which sensor a lens device is related to. The struct
> media_entity_desc does have a group_id field for grouping the sub-devices
> but that's hardly a good way to describe this.

Yeah, it would be good to get the corresponding patches to be merged
to v4l-utils...

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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