Re: [PATCH v11 04/15] media: v4l2-fwnode: add initial connector parsing support

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Sakari,

gentle ping.

Regards,
  Marco

On 19-11-19 12:37, Marco Felsch wrote:
> Hi Sakari,
> 
> On 19-11-16 01:34, Sakari Ailus wrote:
> > Hi Marco,
> > 
> > On Mon, Sep 30, 2019 at 11:38:49AM +0200, Marco Felsch wrote:
> > > The patch adds the initial connector parsing code, so we can move from a
> > > driver specific parsing code to a generic one. Currently only the
> > > generic fields and the analog-connector specific fields are parsed. Parsing
> > > the other connector specific fields can be added by a simple callbacks.
> > > 
> > > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > > ---
> > > [1] https://patchwork.kernel.org/cover/10794703/
> > > 
> > > v10:
> > > - drop V4L2_CONN_HDMI support
> > > - adapt pr_err msg to reflect new state (-> connector is unkown)
> > > 
> > > v9:
> > > - Fix leading semicolon found by kbuild semicolon.cocci
> > > 
> > > v8:
> > > - V4L2_CON_* -> V4L2_CONN_*
> > > - tvnorms -> sdtv-standards
> > > - adapt to new v4l2_fwnode_connector_analog member
> > > - return error in case of V4L2_CONN_HDMI
> > > 
> > > v7:
> > > @Jacopo: I dropped your r b tag becuase of the amount of changes I
> > > made..
> > > 
> > > - drop unnecessary comments
> > > - fix commet style
> > > - s/v4l2_fwnode_connector_conv.name/v4l2_fwnode_connector_conv.compatible/
> > > - make label size variable and drop V4L2_CONNECTOR_MAX_LABEL usage
> > > - do not assign a default label in case of no label was specified
> > > - remove useless /* fall through */ comments
> > > - add support for N connector links
> > > - rename local variables to be more meaningful
> > > - adjust kernedoc
> > > - add v4l2_fwnode_connector_free()
> > > - improve error handling (use different error values)
> > > - make use of pr_warn_once()
> > > 
> > > v6:
> > > - use unsigned count var
> > > - fix comment and style issues
> > > - place '/* fall through */' to correct places
> > > - fix error handling and cleanup by releasing fwnode
> > > - drop vga and dvi parsing support as those connectors are rarely used
> > >   these days
> > > 
> > > v5:
> > > - s/strlcpy/strscpy/
> > > 
> > > v2-v4:
> > > - nothing since the patch was squashed from series [1] into this
> > >   series.
> > > ---
> > >  drivers/media/v4l2-core/v4l2-fwnode.c | 129 ++++++++++++++++++++++++++
> > >  include/media/v4l2-fwnode.h           |  38 ++++++++
> > >  2 files changed, 167 insertions(+)
> > > 
> > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > index 3bd1888787eb..0bfa7cbf78df 100644
> > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > @@ -595,6 +595,135 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> > >  }
> > >  EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> > >  
> > > +static const struct v4l2_fwnode_connector_conv {
> > > +	enum v4l2_connector_type type;
> > > +	const char *compatible;
> > > +} connectors[] = {
> > > +	{
> > > +		.type = V4L2_CONN_COMPOSITE,
> > > +		.compatible = "composite-video-connector",
> > > +	}, {
> > > +		.type = V4L2_CONN_SVIDEO,
> > > +		.compatible = "svideo-connector",
> > > +	},
> > > +};
> > > +
> > > +static enum v4l2_connector_type
> > > +v4l2_fwnode_string_to_connector_type(const char *con_str)
> > > +{
> > > +	unsigned int i;
> > > +
> > > +	for (i = 0; i < ARRAY_SIZE(connectors); i++)
> > > +		if (!strcmp(con_str, connectors[i].compatible))
> > > +			return connectors[i].type;
> > > +
> > > +	return V4L2_CONN_UNKNOWN;
> > > +}
> > > +
> > > +static int
> > > +v4l2_fwnode_connector_parse_analog(struct fwnode_handle *fwnode,
> > > +				   struct v4l2_fwnode_connector *vc)
> > > +{
> > > +	u32 stds;
> > > +	int ret;
> > > +
> > > +	ret = fwnode_property_read_u32(fwnode, "sdtv-standards", &stds);
> > > +
> > > +	/* The property is optional. */
> > > +	vc->connector.analog.sdtv_stds = ret ? V4L2_STD_ALL : stds;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +void v4l2_fwnode_connector_free(struct v4l2_fwnode_connector *connector)
> > > +{
> > > +	unsigned int i;
> > > +
> > > +	if (IS_ERR_OR_NULL(connector))
> > > +		return;
> > > +
> > > +	for (i = 0; i < connector->nr_of_links; i++)
> > > +		v4l2_fwnode_put_link(&connector->links[i]);
> > > +	kfree(connector->links);
> > 
> > Please do set connector->links NULL here. That avoids accidentally double
> > kfree on the pointer.
> 
> Okay, I will do that.
> 
> > > +}
> > > +EXPORT_SYMBOL_GPL(v4l2_fwnode_connector_free);
> > > +
> > > +int v4l2_fwnode_connector_alloc_parse(struct fwnode_handle *fwnode,
> > > +				      struct v4l2_fwnode_connector *connector)
> > > +{
> > > +	struct fwnode_handle *remote_pp, *remote_ep;
> > > +	const char *type_name;
> > > +	unsigned int i = 0, ep_num = 0;
> > > +	int err;
> > > +
> > > +	memset(connector, 0, sizeof(*connector));
> > > +
> > > +	remote_pp = fwnode_graph_get_remote_port_parent(fwnode);
> > > +	if (!remote_pp)
> > > +		return -ENOLINK;
> 
> Should I drop this logic here and force the caller to pass the connector
> endpoint?
> 
> > > +
> > > +	/* Parse all common properties first. */
> > > +	fwnode_graph_for_each_endpoint(remote_pp, remote_ep)
> > > +		ep_num++;
> > 
> > If there are no endpoints, ep_num will be zero and kmalloc_array() will
> > return NULL? There should be a way there are no endpoints, rather than
> > returning -ENOMEM.
> 
> Hm.. using the current implementation (please see my above comment)
> ensures that there is always one link but if I change that I need to
> check this, good point.
> 
> > > +
> > > +	connector->nr_of_links = ep_num;
> > > +	connector->links = kmalloc_array(ep_num, sizeof(*connector->links),
> > > +					 GFP_KERNEL);
> > > +	if (!connector->links) {
> > > +		err = -ENOMEM;
> > > +		goto err_put_fwnode;
> > > +	}
> > > +
> > > +	fwnode_graph_for_each_endpoint(remote_pp, remote_ep) {
> > > +		err = v4l2_fwnode_parse_link(remote_ep, &connector->links[i]);
> > 
> > If you start parsing a connector starting from another device connected to
> > it, nothing seems to prevent parsing the same links twice, in case the
> > connector is connected to more than one sub-device.
> > 
> > Or do I miss something crucial here?
> 
> That is true because currently each sub-device implements their own
> connector parsing/handling stuff.. What i wanted to address with this
> code is that one sub-device can have multiple links to one connector
> e.g. s-video connectors (1xluma 1xchroma). I don't know how to handle
> this without a simple connector device.
> 
> Regards,
>   Marco
> 
> > > +		if (err) {
> > > +			fwnode_handle_put(remote_ep);
> > > +			goto err_free_links;
> > > +		}
> > > +		i++;
> > > +	}
> > > +
> > > +	/*
> > > +	 * Links reference counting guarantees access -> no duplication needed
> > > +	 */
> > > +	fwnode_property_read_string(remote_pp, "label", &connector->label);
> > > +
> > > +	/* The connector-type is stored within the compatible string. */
> > > +	err = fwnode_property_read_string(remote_pp, "compatible", &type_name);
> > > +	if (err) {
> > > +		err = -EINVAL;
> > > +		goto err_free_links;
> > > +	}
> > > +	connector->type = v4l2_fwnode_string_to_connector_type(type_name);
> > > +
> > > +	/* Now parse the connector specific properties. */
> > > +	switch (connector->type) {
> > > +	case V4L2_CONN_COMPOSITE:
> > > +	case V4L2_CONN_SVIDEO:
> > > +		err = v4l2_fwnode_connector_parse_analog(remote_pp, connector);
> > > +		break;
> > > +	case V4L2_CONN_UNKNOWN:
> > > +	default:
> > > +		pr_err("Unknown connector type\n");
> > > +		err = -EINVAL;
> > > +		goto err_free_links;
> > > +	}
> > > +
> > > +	fwnode_handle_put(remote_pp);
> > > +
> > > +	return err;
> > > +
> > > +err_free_links:
> > > +	for (i = 0; i < ep_num; i++)
> > > +		v4l2_fwnode_put_link(&connector->links[i]);
> > > +	kfree(connector->links);
> > > +err_put_fwnode:
> > > +	fwnode_handle_put(remote_pp);
> > > +
> > > +	return err;
> > > +}
> > > +EXPORT_SYMBOL_GPL(v4l2_fwnode_connector_alloc_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 65da646b579e..800302aa84d8 100644
> > > --- a/include/media/v4l2-fwnode.h
> > > +++ b/include/media/v4l2-fwnode.h
> > > @@ -276,6 +276,44 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> > >   */
> > >  void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> > >  
> > > +/**
> > > + * v4l2_fwnode_connector_free() - free the V4L2 connector acquired by
> > > + * v4l2_fwnode_parse_connector()
> > 
> > This would be nicer aligned with the text after the dash.
> > 
> > > + * @connector: the V4L2 connector the resources of which are to be released
> > > + *
> > > + * Drop references to the connection link partners and free the memory allocated
> > > + * by v4l2_fwnode_parse_connector() call.
> > > + *
> > > + * It is safe to call this function with NULL argument or on a V4L2 connector
> > > + * the parsing of which failed.
> > > + */
> > > +void v4l2_fwnode_connector_free(struct v4l2_fwnode_connector *connector);
> > > +
> > > +/**
> > > + * v4l2_fwnode_parse_connector() - parse the connector on endpoint
> > 
> > The name is different from the actual function.
> > 
> > > + * @fwnode: pointer to the endpoint's fwnode handle where the connector is
> > > + *          connected to
> > > + * @connector: pointer to the V4L2 fwnode connector data structure
> > > + *
> > > + * Fill the connector data structure with the connector type, label, all found
> > > + * links between the host and the connector as well as connector specific data.
> > > + * Since the label is optional it can be %NULL if no one was found.
> > > + *
> > > + * A reference is taken to both the connector and the connector destination
> > > + * where the connector belongs to. This must be dropped when no longer needed.
> > > + * Also the memory it has allocated to store the variable size data must be
> > > + * freed. Both dropping the references and freeing the memory is done by
> > > + * v4l2_fwnode_connector_free().
> > > + *
> > > + * Return:
> > > + * * %0 on success or a negative error code on failure:
> > > + * * %-ENOMEM if memory allocation failed
> > > + * * %-ENOLINK if the connector can't be found
> > > + * * %-EINVAL on parsing failure
> > 
> > Could this error code tell the endpoint is not connected to a connector?
> > 
> > I think the perfectly suitable error code for this would be -ENOTCONN. :-D
> > 
> > > + */
> > > +int v4l2_fwnode_connector_alloc_parse(struct fwnode_handle *fwnode,
> > > +				      struct v4l2_fwnode_connector *connector);
> > > +
> > >  /**
> > >   * typedef parse_endpoint_func - Driver's callback function to be called on
> > >   *	each V4L2 fwnode endpoint.
> > > 
> > 
> > -- 
> > Regards,
> > 
> > Sakari Ailus
> > sakari.ailus@linux.intel.com
> > 
> 
> -- 
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> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |