Re: [PATCH v2 06/30] media: entity: Use pad as the starting point for a pipeline

[Sakari Ailus <sakari.ailus@linux.intel.com>]

On Tue, Jan 22, 2019 at 05:37:15PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Tue, Jan 22, 2019 at 05:31:34PM +0200, Sakari Ailus wrote:
> > On Wed, Jan 16, 2019 at 12:54:20AM +0200, Laurent Pinchart wrote:
> > > On Fri, Nov 02, 2018 at 12:31:20AM +0100, Niklas Söderlund wrote:
> > >> From: Sakari Ailus <sakari.ailus@linux.intel.com>
> > >> 
> > >> The pipeline will be moved from the entity to the pads; reflect this in
> > >> the media pipeline function API.
> > > 
> > > Will be moved, or has been moved ?
> > 
> > Will be, as it's not yet in this patch.
> 
> [PATCH v2 05/30] media: entity: Move the pipeline from entity to pads

Oh, I thought it was the other way. Well, "has been" then? :-)

> 
> > >> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > >> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> > >> ---
> > >>  Documentation/media/kapi/mc-core.rst          |  6 ++--
> > >>  drivers/media/media-entity.c                  | 25 +++++++-------
> > >>  drivers/media/pci/intel/ipu3/ipu3-cio2.c      |  6 ++--
> > >>  .../media/platform/exynos4-is/fimc-capture.c  |  8 ++---
> > >>  .../platform/exynos4-is/fimc-isp-video.c      |  8 ++---
> > >>  drivers/media/platform/exynos4-is/fimc-lite.c |  8 ++---
> > >>  drivers/media/platform/omap3isp/ispvideo.c    |  6 ++--
> > >>  .../media/platform/qcom/camss/camss-video.c   |  6 ++--
> > >>  drivers/media/platform/rcar-vin/rcar-dma.c    |  6 ++--
> > >>  .../media/platform/s3c-camif/camif-capture.c  |  6 ++--
> > >>  drivers/media/platform/vimc/vimc-capture.c    |  6 ++--
> > >>  drivers/media/platform/vsp1/vsp1_video.c      |  6 ++--
> > >>  drivers/media/platform/xilinx/xilinx-dma.c    |  6 ++--
> > >>  drivers/media/usb/au0828/au0828-core.c        |  4 +--
> > >>  drivers/staging/media/imx/imx-media-utils.c   |  6 ++--
> > >>  drivers/staging/media/omap4iss/iss_video.c    |  6 ++--
> > >>  include/media/media-entity.h                  | 33 ++++++++++---------
> > >>  17 files changed, 76 insertions(+), 76 deletions(-)
> > >> 
> > >> diff --git a/Documentation/media/kapi/mc-core.rst b/Documentation/media/kapi/mc-core.rst
> > >> index 849b87439b7a9772..ede7e946f6a82ac0 100644
> > >> --- a/Documentation/media/kapi/mc-core.rst
> > >> +++ b/Documentation/media/kapi/mc-core.rst
> > >> @@ -211,11 +211,11 @@ When starting streaming, drivers must notify all entities in the pipeline to
> > >>  prevent link states from being modified during streaming by calling
> > >>  :c:func:`media_pipeline_start()`.
> > >>  
> > >> -The function will mark all entities connected to the given entity through
> > >> -enabled links, either directly or indirectly, as streaming.
> > >> +The function will mark all entities connected to the given pad through
> > >> +enabled routes and links, either directly or indirectly, as streaming.
> > > 
> > > That's not really correct, it doesn't mark entities, but pads. I think
> > > this section of the documentation needs to be rewritten based on the new
> > > model of an entity being part of multiple pipelines. s/entity/pad/ isn't
> > > enough, there's a whole new semantics.
> > 
> > I'd say it's correct. Note that this function just beings the walk from a
> > given pad, it doesn't make other changes --- there are further patches
> > thought that do.
> 
> OK, it might be a change in progress, but the documentation still has to
> be rewritten to explain the new model. We need at least one or two new
> paragraphs in addition to the s/entity/pad/.

There are several patches that would need to change the documentation "a
little". I wonder if it'd be better to just have one patch in the end
updating the documentation.

> 
> > >>  The struct :c:type:`media_pipeline` instance pointed to by
> > >> -the pipe argument will be stored in every entity in the pipeline.
> > >> +the pipe argument will be stored in every pad in the pipeline.
> > >>  Drivers should embed the struct :c:type:`media_pipeline`
> > >>  in higher-level pipeline structures and can then access the
> > >>  pipeline through the struct :c:type:`media_entity`
> > >> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> > >> index 13260149c4dfc90c..f2fa0b7826dbc2f3 100644
> > >> --- a/drivers/media/media-entity.c
> > >> +++ b/drivers/media/media-entity.c
> > >> @@ -411,12 +411,11 @@ EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
> > >>   * Pipeline management
> > >>   */
> > >>  
> > >> -__must_check int __media_pipeline_start(struct media_entity *entity,
> > >> +__must_check int __media_pipeline_start(struct media_pad *pad,
> > >>  					struct media_pipeline *pipe)
> > >>  {
> > >> -	struct media_device *mdev = entity->graph_obj.mdev;
> > >> +	struct media_device *mdev = pad->graph_obj.mdev;
> > >>  	struct media_graph *graph = &pipe->graph;
> > >> -	struct media_pad *pad = entity->pads;
> > >>  	struct media_pad *pad_err = pad;
> > >>  	struct media_link *link;
> > >>  	int ret = 0;
> > >> @@ -549,24 +548,23 @@ __must_check int __media_pipeline_start(struct media_entity *entity,
> > >>  }
> > >>  EXPORT_SYMBOL_GPL(__media_pipeline_start);
> > >>  
> > >> -__must_check int media_pipeline_start(struct media_entity *entity,
> > >> +__must_check int media_pipeline_start(struct media_pad *pad,
> > >>  				      struct media_pipeline *pipe)
> > >>  {
> > >> -	struct media_device *mdev = entity->graph_obj.mdev;
> > >> +	struct media_device *mdev = pad->graph_obj.mdev;
> > >>  	int ret;
> > >>  
> > >>  	mutex_lock(&mdev->graph_mutex);
> > >> -	ret = __media_pipeline_start(entity, pipe);
> > >> +	ret = __media_pipeline_start(pad, pipe);
> > >>  	mutex_unlock(&mdev->graph_mutex);
> > >>  	return ret;
> > >>  }
> > >>  EXPORT_SYMBOL_GPL(media_pipeline_start);
> > >>  
> > >> -void __media_pipeline_stop(struct media_entity *entity)
> > >> +void __media_pipeline_stop(struct media_pad *pad)
> > >>  {
> > >> -	struct media_pipeline *pipe = entity->pads->pipe;
> > >> +	struct media_pipeline *pipe = pad->pipe;
> > >>  	struct media_graph *graph = &pipe->graph;
> > >> -	struct media_pad *pad;
> > >>  
> > >>  	/*
> > >>  	 * If the following check fails, the driver has performed an
> > >> @@ -575,9 +573,10 @@ void __media_pipeline_stop(struct media_entity *entity)
> > >>  	if (WARN_ON(!pipe))
> > >>  		return;
> > >>  
> > >> -	media_graph_walk_start(graph, entity->pads);
> > >> +	media_graph_walk_start(graph, pad);
> > >>  
> > >>  	while ((pad = media_graph_walk_next(graph))) {
> > >> +		struct media_entity *entity = pad->entity;
> > > 
> > > It looks like this line is a bug fix for a previous patch in the series.
> > 
> > Yes, so it seems to be. The previous patch appears to remove it.
> > 
> > >>  		unsigned int i;
> > >>  
> > >>  		for (i = 0; i < entity->num_pads; i++) {
> > >> @@ -598,12 +597,12 @@ void __media_pipeline_stop(struct media_entity *entity)
> > >>  }
> > >>  EXPORT_SYMBOL_GPL(__media_pipeline_stop);
> > >>  
> > >> -void media_pipeline_stop(struct media_entity *entity)
> > >> +void media_pipeline_stop(struct media_pad *pad)
> > >>  {
> > >> -	struct media_device *mdev = entity->graph_obj.mdev;
> > >> +	struct media_device *mdev = pad->graph_obj.mdev;
> > >>  
> > >>  	mutex_lock(&mdev->graph_mutex);
> > >> -	__media_pipeline_stop(entity);
> > >> +	__media_pipeline_stop(pad);
> > >>  	mutex_unlock(&mdev->graph_mutex);
> > >>  }
> > >>  EXPORT_SYMBOL_GPL(media_pipeline_stop);
> > > 
> > > [snip]
> > > 
> > >> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> > >> index ca0b79288ea7fd11..8378f700389635ea 100644
> > >> --- a/include/media/media-entity.h
> > >> +++ b/include/media/media-entity.h
> > >> @@ -965,53 +965,54 @@ struct media_pad *media_graph_walk_next(struct media_graph *graph);
> > >>  
> > >>  /**
> > >>   * media_pipeline_start - Mark a pipeline as streaming
> > >> - * @entity: Starting entity
> > >> - * @pipe: Media pipeline to be assigned to all entities in the pipeline.
> > >> + * @pad: Starting pad
> > >> + * @pipe: Media pipeline to be assigned to all pads in the pipeline.
> > >>   *
> > >> - * Mark all entities connected to a given entity through enabled links, either
> > >> - * directly or indirectly, as streaming. The given pipeline object is assigned
> > >> - * to every entity in the pipeline and stored in the media_entity pipe field.
> > >> + * Mark all pads connected to a given pad through enabled
> > >> + * routes or links, either directly or indirectly, as streaming. The
> > >> + * given pipeline object is assigned to every pad in the pipeline
> > >> + * and stored in the media_pad pipe field.
> > > 
> > > Reflowing text to the 80 columns limit ?
> > 
> > Agreed.
> > 
> > >>   *
> > >>   * Calls to this function can be nested, in which case the same number of
> > >>   * media_pipeline_stop() calls will be required to stop streaming. The
> > >>   * pipeline pointer must be identical for all nested calls to
> > >>   * media_pipeline_start().
> > >>   */
> > >> -__must_check int media_pipeline_start(struct media_entity *entity,
> > >> +__must_check int media_pipeline_start(struct media_pad *pad,
> > >>  				      struct media_pipeline *pipe);
> > >>  /**
> > >>   * __media_pipeline_start - Mark a pipeline as streaming
> > >>   *
> > >> - * @entity: Starting entity
> > >> - * @pipe: Media pipeline to be assigned to all entities in the pipeline.
> > >> + * @pad: Starting pad
> > >> + * @pipe: Media pipeline to be assigned to all pads in the pipeline.
> > >>   *
> > >>   * ..note:: This is the non-locking version of media_pipeline_start()
> > >>   */
> > >> -__must_check int __media_pipeline_start(struct media_entity *entity,
> > >> +__must_check int __media_pipeline_start(struct media_pad *pad,
> > >>  					struct media_pipeline *pipe);
> > >>  
> > >>  /**
> > >>   * media_pipeline_stop - Mark a pipeline as not streaming
> > >> - * @entity: Starting entity
> > >> + * @pad: Starting pad
> > >>   *
> > >> - * Mark all entities connected to a given entity through enabled links, either
> > >> - * directly or indirectly, as not streaming. The media_entity pipe field is
> > >> - * reset to %NULL.
> > >> + * Mark all pads connected to a given pad through enabled routes or
> > >> + * links, either directly or indirectly, as not streaming. The
> > >> + * media_pad pipe field is reset to %NULL.
> > > 
> > > Ditto.
> > > 
> > > With the above fixed,
> > > 
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > 
> > >>   *
> > >>   * If multiple calls to media_pipeline_start() have been made, the same
> > >>   * number of calls to this function are required to mark the pipeline as not
> > >>   * streaming.
> > >>   */
> > >> -void media_pipeline_stop(struct media_entity *entity);
> > >> +void media_pipeline_stop(struct media_pad *pad);
> > >>  
> > >>  /**
> > >>   * __media_pipeline_stop - Mark a pipeline as not streaming
> > >>   *
> > >> - * @entity: Starting entity
> > >> + * @pad: Starting pad
> > >>   *
> > >>   * .. note:: This is the non-locking version of media_pipeline_stop()
> > >>   */
> > >> -void __media_pipeline_stop(struct media_entity *entity);
> > >> +void __media_pipeline_stop(struct media_pad *pad);
> > >>  
> > >>  /**
> > >>   * media_devnode_create() - creates and initializes a device node interface
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Sakari Ailus
sakari.ailus@linux.intel.com