Re: [PATCH] media: i2c: adv7343: fix the DT binding properties

[Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

On Monday 23 September 2013 08:18:52 Prabhakar Lad wrote:
> On Fri, Sep 20, 2013 at 3:22 PM, Sylwester Nawrocki wrote:
> > On 09/20/2013 10:11 AM, Prabhakar Lad wrote:
> >> OK I will, just send out a fix up patch which fixes the mismatch between
> >> names for the rc-cycle, and later send out a patch which removes the
> >> platform data usage for next release with proper DT bindings.
> > 
> > I think the binding need to be fully corrected now, I just meant to not
> > touch the board file, i.e. leave non-dt support unchanged.
> 
> Ok
> 
> >> I'm OK with making regulator properties as optional, But still it would
> >> change the meaning of what DT is, we know that the VDD/VDD_IO .. etc
> >> pins are required properties (but still making them as optional) :-(
> >> 
> >> I think there might several devices where this situation may arise so
> >> just thinking of a alternative solution.
> >> 
> >> say we have property 'software-regulator' which takes true/false(0/1)
> >> If set to true we make the regulators as required property or else we
> >> assume it is handled and ignore it ?
> > 
> > I don't think this is a good idea. You would have to add a similar
> > platform data flag for non-dt, it doesn't sound right. I can see two
> > options here:
> > 
> > 1. Make the regulator properties mandatory and, e.g. define a fixed
> >    voltage GPIO regulator in DT with an empty 'gpio' property. Then
> >    pass a phandle to that regulator in the adv7343 *-supply properties.
> >    For non-dt similarly a fixed voltage regulator(s) and voltage
> >    supplies  would need to be defined in the board files.
> > 
> > 2. Make the properties optional and use (devm_)regulator_get_optional()
> >    calls in the driver (a recently added function). I must admit I don't
> >    fully understand description of this function, it currently looks
> >    pretty much same as (devm_)regulator_get(). Thus the driver would
> >    need to be handling regulator supplies only when non ERR_PTR() is
> >    returned from regulator_get_optional() and otherwise assume a non
> >    critical error. There is already quite a few example occurrences of
> >    regulator_get_optional() usage.
> 
> Thanks for pointing it I'll choose option 2 and post the patch.

Isn't regulator_get_optional() intended for devices that can have supplies 
unconnected in normal use ? The ADV7343 supplies are mandatory from a hardware 
point of view, so I think we should use regulator_get(). Otherwise the driver 
won't be able to tell the difference between a regulator that isn't present 
yet (for instance because the regulator device/driver hasn't been probed yet), 
which should result in deferred probing, and an always-on regulator that has 
been left out.

-- 
Regards,

Laurent Pinchart

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