Re: [PATCH v13 17/25] v4l: fwnode: Add a helper function for parsing generic references

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

Hi Sakari,

On Tuesday, 19 September 2017 16:04:53 EEST Sakari Ailus wrote:
> On Tue, Sep 19, 2017 at 03:19:59PM +0300, Laurent Pinchart wrote:
> > On Friday, 15 September 2017 17:17:16 EEST Sakari Ailus wrote:
> > > Add function v4l2_fwnode_reference_parse() for parsing them as async
> > > sub-devices. This can be done on e.g. flash or lens async sub-devices
> > > that are not part of but are associated with a sensor.
> > > 
> > > Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > > ---
> > > 
> > >  drivers/media/v4l2-core/v4l2-fwnode.c | 69 ++++++++++++++++++++++++++++
> > >  1 file changed, 69 insertions(+)
> > > 
> > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > b/drivers/media/v4l2-core/v4l2-fwnode.c index 44ee35f6aad5..65e84ea1cc35
> > > 100644
> > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > @@ -498,6 +498,75 @@ int
> > > v4l2_async_notifier_parse_fwnode_endpoints_by_port( }
> > > 
> > >  EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints_by_port);
> > > 
> > > +/*
> > > + * v4l2_fwnode_reference_parse - parse references for async sub-devices
> > > + * @dev: the device node the properties of which are parsed for
> > > references
> > > + * @notifier: the async notifier where the async subdevs will be added
> > > + * @prop: the name of the property
> > > + *
> > > + * Return: 0 on success
> > > + *	   -ENOENT if no entries were found
> > > + *	   -ENOMEM if memory allocation failed
> > > + *	   -EINVAL if property parsing failed
> > > + */
> > > +static int v4l2_fwnode_reference_parse(
> > > +	struct device *dev, struct v4l2_async_notifier *notifier,
> > > +	const char *prop)
> > > +{
> > > +	struct fwnode_reference_args args;
> > > +	unsigned int index;
> > > +	int ret;
> > > +
> > > +	for (index = 0;
> > > +	     !(ret = fwnode_property_get_reference_args(
> > > +		       dev_fwnode(dev), prop, NULL, 0, index, &args));
> > > +	     index++)
> > > +		fwnode_handle_put(args.fwnode);
> > 
> > This seems to indicate that the fwnode API is missing a function to count
> > the number of references in a property. Should that be fixed ?
> 
> I can send a patch adding that.
> 
> OF has one available but it's only for cases where the number of integer
> arguments isn't fixed.

Yes, in all other cases the size of one reference is known (it's the sum of 
the sizes of all arguments), so the number of references can be computed with 
size(property) / size(reference).

> > The rest looks OK to me.
> > 
> > > +	if (!index)
> > > +		return -ENOENT;
> > > +
> > > +	/*
> > > +	 * Note that right now both -ENODATA and -ENOENT may signal
> > > +	 * out-of-bounds access. Return the error in cases other than that.
> > > +	 */
> > > +	if (ret != -ENOENT && ret != -ENODATA)
> > > +		return ret;
> > > +
> > > +	ret = v4l2_async_notifier_realloc(notifier,
> > > +					  notifier->num_subdevs + index);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	for (index = 0; !fwnode_property_get_reference_args(
> > > +		     dev_fwnode(dev), prop, NULL, 0, index, &args);
> > > +	     index++) {
> > > +		struct v4l2_async_subdev *asd;
> > > +
> > > +		if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs)) {
> > > +			ret = -EINVAL;
> > > +			goto error;
> > > +		}
> > > +
> > > +		asd = kzalloc(sizeof(*asd), GFP_KERNEL);
> > > +		if (!asd) {
> > > +			ret = -ENOMEM;
> > > +			goto error;
> > > +		}
> > > +
> > > +		notifier->subdevs[notifier->num_subdevs] = asd;
> > > +		asd->match.fwnode.fwnode = args.fwnode;
> > > +		asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > > +		notifier->num_subdevs++;
> > > +	}
> > > +
> > > +	return 0;
> > > +
> > > +error:
> > > +	fwnode_handle_put(args.fwnode);
> > > +	return ret;
> > > +}
> > > +
> > > 
> > >  MODULE_LICENSE("GPL");
> > >  MODULE_AUTHOR("Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>");
> > >  MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>");


-- 
Regards,

Laurent Pinchart

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