Re: [RFC/PATCH 06/13] media: s5p-fimc: Add device tree support for FIMC-LITE

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

Hi Sylwester

On Tue, 17 Jul 2012, Sylwester Nawrocki wrote:

> On 07/16/2012 11:15 AM, Guennadi Liakhovetski wrote:
> > > --- a/Documentation/devicetree/bindings/camera/soc/samsung-fimc.txt
> > > +++ b/Documentation/devicetree/bindings/camera/soc/samsung-fimc.txt
> > > @@ -39,6 +39,21 @@ Required properties:
> > >   	       depends on the SoC revision. For S5PV210 valid values are:
> > >   	       0...2, for Exynos4x1x: 0...3.
> > > 
> > > +
> > > +'fimc-lite' device node
> > > +-----------------------
> > > +
> > > +Required properties:
> > > +
> > > +- compatible : should be one of:
> > > +		"samsung,exynos4212-fimc";
> > > +		"samsung,exynos4412-fimc";
> > > +- reg	     : physical base address and size of the device's memory
> > > mapped
> > > +	       registers;
> > > +- interrupts : should contain FIMC-LITE interrupt;
> > > +- cell-index : FIMC-LITE IP instance index;
> > 
> > Same as in an earlier patch - not sure this is needed.
> 
> It is needed for setting up a pipeline of multiple sub-device
> within a SoC. As I commented on patch 2/13 I'd like to replace
> this with proper entries in the "aliases" node. Some sub-devices
> have registers that these indexes need to be directly written to.

Aha, so, these are not purely software indices, that you just use to 
identify your devices, these are actual hardware values? You really have 
to write, e.g., "1" into a resizer register to connect it to a certain 
capture engine? Ok, in this case it indeed might make sense to have these 
values in the DT. Not sure how best to call these properties, or whether 
aliases is the best solution, but that's already a detail. And btw, if you 
do decide to keep this as a property, maybe this is one of the cases, 
where you'd want to mark it with your hardware type, like "fimc,cell-id" 
or similar?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/