Re: [PATCH v3 06/11] media: v4l2-fwnode: Add helper to parse device properties

[Jacopo Mondi <jacopo@jmondi.org>]

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Hi Hans,

On Fri, Sep 13, 2019 at 04:08:10PM +0200, Hans Verkuil wrote:
> On 9/12/19 10:10 PM, Jacopo Mondi wrote:
> > Add an helper function to parse common device properties in the same
> > way as v4l2_fwnode_endpoint_parse() parses common endpoint properties.
> >
> > Initially parse the 'rotation' and 'location' properties from the
>
> Just drop 'Initially'. It's redundant.
>
> > firmware interface.
> >
> > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> > ---
> >  drivers/media/v4l2-core/v4l2-fwnode.c | 42 +++++++++++++++++++++++++++
> >  include/media/v4l2-fwnode.h           | 40 +++++++++++++++++++++++++
> >  2 files changed, 82 insertions(+)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 3bd1888787eb..d325a2d5c088 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -595,6 +595,48 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> >
> > +int v4l2_fwnode_device_parse(struct device *dev,
> > +			     struct v4l2_fwnode_device_properties *props)
> > +{
> > +	struct fwnode_handle *fwnode = dev_fwnode(dev);
> > +	u32 val;
> > +	int ret;
> > +
> > +	memset(props, 0, sizeof(*props));
> > +
> > +	dev_dbg(dev, "===== begin V4L2 device properties parsing\n");
> > +	ret = fwnode_property_read_u32(fwnode, "location", &val);
> > +	if (!ret) {
> > +		switch (val) {
> > +		case V4L2_FWNODE_LOCATION_FRONT:
> > +		case V4L2_FWNODE_LOCATION_BACK:
> > +		case V4L2_FWNODE_LOCATION_EXTERNAL:
> > +			break;
> > +		default:
> > +			dev_warn(dev, "Unsupported device location: %u\n", val);
> > +			return -EINVAL;
> > +		}
> > +
> > +		props->location = val;
> > +		dev_dbg(dev, "device location: %u\n", val);
> > +	}
> > +
> > +	ret = fwnode_property_read_u32(fwnode, "rotation", &val);
> > +	if (!ret) {
> > +		if (val >= 360 || val % 90) {
> > +			dev_warn(dev, "Unsupported device rotation: %u\n", val);
> > +			return -EINVAL;
> > +		}
> > +
> > +		props->rotation = val;
> > +		dev_dbg(dev, "device rotation: %u\n", val);
> > +	}
> > +	dev_dbg(dev, "===== end V4L2 device properties parsing\n");
>
> Are these dev_dbg lines really needed? It seems a bit overkill to me.
>

It's the same debug output we have in v4l2_fwnode_endpoint_parse() so
I tried to be consistent. Should I drop it?

> What if rotation is set, but not location. Then location defaults to Front.
> Is that what we want, or should we add an UNKNOWN location?
>

As you have noticed I have added a value to encode UNKNOW in the later
patch, I should probably add them in this one as you suggested ?

> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_fwnode_device_parse);
> > +
> >  static int
> >  v4l2_async_notifier_fwnode_parse_endpoint(struct device *dev,
> >  					  struct v4l2_async_notifier *notifier,
> > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > index f6a7bcd13197..86af6d9d11fe 100644
> > --- a/include/media/v4l2-fwnode.h
> > +++ b/include/media/v4l2-fwnode.h
> > @@ -109,6 +109,28 @@ struct v4l2_fwnode_endpoint {
> >  	unsigned int nr_of_link_frequencies;
> >  };
> >
> > +/**
> > + * enum v4l2_fwnode_location - possible device locations
> > + * @V4L2_FWNODE_LOCATION_FRONT: device installed on the front side
> > + * @V4L2_FWNODE_LOCATION_BACK: device installed on the back side
> > + * @V4L2_FWNODE_LOCATION_EXTERNAL: device externally located
> > + */
> > +enum v4l2_fwnode_location {
> > +	V4L2_FWNODE_LOCATION_FRONT,
> > +	V4L2_FWNODE_LOCATION_BACK,
> > +	V4L2_FWNODE_LOCATION_EXTERNAL
> > +};
> > +
> > +/**
> > + * struct v4l2_fwnode_device_properties - fwnode device properties
> > + * @location: device location. See &enum v4l2_fwnode_location
> > + * @rotation: device rotation
> > + */
> > +struct v4l2_fwnode_device_properties {
> > +	enum v4l2_fwnode_location location;
> > +	unsigned int rotation;
> > +};
> > +
> >  /**
> >   * struct v4l2_fwnode_link - a link between two endpoints
> >   * @local_node: pointer to device_node of this endpoint
> > @@ -233,6 +255,24 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> >   */
> >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> >
> > +/**
> > + * v4l2_fwnode_device_parse() - parse fwnode device properties
> > + * @dev: pointer to &struct device
> > + * @props: pointer to &struct v4l2_fwnode_device_properties where to store the
> > + *	   parsed properties values
> > + *
> > + * This function parses and validates the V4L2 fwnode device properties from
> > + * the firmware interface. It is responsibility of the caller to allocate a
> > + * valid @struct v4l2_fwnode_device_properties structure and provide a pointer
> > + * to it in the @props parameter.
> > + *
> > + * Return:
> > + *	% 0 on success
> > + *	%-EINVAL if a parsed property value is not valid
> > + */
> > +int v4l2_fwnode_device_parse(struct device *dev,
> > +			     struct v4l2_fwnode_device_properties *props);
> > +
> >  /**
> >   * typedef parse_endpoint_func - Driver's callback function to be called on
> >   *	each V4L2 fwnode endpoint.
> >
>
> Regards,
>
> 	Hans

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