Re: [PATCH] media: Accept non-subdev sinks in v4l2_create_fwnode_links_to_pad()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Vaishnav,

On Thu, Apr 13, 2023 at 06:51:23PM +0530, Vaishnav Achath wrote:
> Hi Laurent,
> 
> Thank you for the patch, sorry for the delay in response,
> 
> On 24/03/23 16:05, Laurent Pinchart wrote:
> > The v4l2_create_fwnode_links_to_pad() helper requires the sink pad
> > passed to it to belong to a subdev. This requirement can be lifted
> > easily. Make the function usable for non-subdev sinks, which allows
> > using it with video_device sinks.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  drivers/media/v4l2-core/v4l2-mc.c | 15 ++++++---------
> >  include/media/v4l2-mc.h           |  8 ++++----
> >  2 files changed, 10 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> > index b01474717dca..bf0c18100664 100644
> > --- a/drivers/media/v4l2-core/v4l2-mc.c
> > +++ b/drivers/media/v4l2-core/v4l2-mc.c
> > @@ -313,14 +313,11 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> >  				    struct media_pad *sink, u32 flags)
> >  {
> >  	struct fwnode_handle *endpoint;
> > -	struct v4l2_subdev *sink_sd;
> >  
> >  	if (!(sink->flags & MEDIA_PAD_FL_SINK) ||
> >  	    !is_media_entity_v4l2_subdev(sink->entity))
> 
> should we drop the second check here also, i.e
> 
> !is_media_entity_v4l2_subdev(sink->entity)
> 
> to accept non-subdev sinks? is my understanding correct?

You're absolutely right. The patch has been merged already I'm afraid.
Would you like to submit a fix, or should I do so ? In the latter case,
can I include a Reported-by tag with your name ?

> >  		return -EINVAL;
> >  
> > -	sink_sd = media_entity_to_v4l2_subdev(sink->entity);
> > -
> >  	fwnode_graph_for_each_endpoint(dev_fwnode(src_sd->dev), endpoint) {
> >  		struct fwnode_handle *remote_ep;
> >  		int src_idx, sink_idx, ret;
> > @@ -340,7 +337,7 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> >  		 * ask the sink to verify it owns the remote endpoint,
> >  		 * and translate to a sink pad.
> >  		 */
> > -		sink_idx = media_entity_get_fwnode_pad(&sink_sd->entity,
> > +		sink_idx = media_entity_get_fwnode_pad(sink->entity,
> >  						       remote_ep,
> >  						       MEDIA_PAD_FL_SINK);
> >  		fwnode_handle_put(remote_ep);
> > @@ -362,17 +359,17 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> >  		if (media_entity_find_link(src, sink))
> >  			continue;
> >  
> > -		dev_dbg(sink_sd->dev, "creating link %s:%d -> %s:%d\n",
> > +		dev_dbg(src_sd->dev, "creating link %s:%d -> %s:%d\n",
> >  			src_sd->entity.name, src_idx,
> > -			sink_sd->entity.name, sink_idx);
> > +			sink->entity->name, sink_idx);
> >  
> >  		ret = media_create_pad_link(&src_sd->entity, src_idx,
> > -					    &sink_sd->entity, sink_idx, flags);
> > +					    sink->entity, sink_idx, flags);
> >  		if (ret) {
> > -			dev_err(sink_sd->dev,
> > +			dev_err(src_sd->dev,
> >  				"link %s:%d -> %s:%d failed with %d\n",
> >  				src_sd->entity.name, src_idx,
> > -				sink_sd->entity.name, sink_idx, ret);
> > +				sink->entity->name, sink_idx, ret);
> >  
> >  			fwnode_handle_put(endpoint);
> >  			return ret;
> > diff --git a/include/media/v4l2-mc.h b/include/media/v4l2-mc.h
> > index c181685923d5..b39586dfba35 100644
> > --- a/include/media/v4l2-mc.h
> > +++ b/include/media/v4l2-mc.h
> > @@ -87,17 +87,17 @@ int v4l_vb2q_enable_media_source(struct vb2_queue *q);
> >  
> >  /**
> >   * v4l2_create_fwnode_links_to_pad - Create fwnode-based links from a
> > - *                                   source subdev to a sink subdev pad.
> > + *                                   source subdev to a sink pad.
> >   *
> >   * @src_sd: pointer to a source subdev
> > - * @sink:  pointer to a subdev sink pad
> > + * @sink:  pointer to a sink pad
> >   * @flags: the link flags
> >   *
> >   * This function searches for fwnode endpoint connections from a source
> >   * subdevice to a single sink pad, and if suitable connections are found,
> >   * translates them into media links to that pad. The function can be
> > - * called by the sink subdevice, in its v4l2-async notifier subdev bound
> > - * callback, to create links from a bound source subdevice.
> > + * called by the sink, in its v4l2-async notifier bound callback, to create
> > + * links from a bound source subdevice.
> >   *
> >   * The @flags argument specifies the link flags. The caller shall ensure that
> >   * the flags are valid regardless of the number of links that may be created.

-- 
Regards,

Laurent Pinchart