Hi Mauro,
On Thursday 09 September 2010 02:46:45 Mauro Carvalho Chehab wrote:
> Em 20-08-2010 12:29, Laurent Pinchart escreveu:
> > From: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> >
> > Add media entity graph traversal. The traversal follows active links by
> > depth first. Traversing graph backwards is prevented by comparing the
> > next possible entity in the graph with the previous one. Multiply
> > connected graphs are thus not supported.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > Signed-off-by: Vimarsh Zutshi <vimarsh.zutshi@xxxxxxxxx>
> > ---
> >
> > Documentation/media-framework.txt | 40 +++++++++++++
> > drivers/media/media-entity.c | 115
> > +++++++++++++++++++++++++++++++++++++ include/media/media-entity.h
> > | 15 +++++
> > 3 files changed, 170 insertions(+), 0 deletions(-)
> >
> > diff --git a/Documentation/media-framework.txt
> > b/Documentation/media-framework.txt index 35d74e4..a599824 100644
> > --- a/Documentation/media-framework.txt
> > +++ b/Documentation/media-framework.txt
> > @@ -238,3 +238,43 @@ Links have flags that describe the link capabilities
> > and state.
> >
> > MEDIA_LINK_FLAG_ACTIVE must also be set since an immutable link is
> > always active.
> >
> > +
> > +Graph traversal
> > +---------------
> > +
> > +The media framework provides APIs to iterate over entities in a graph.
> > +
> > +To iterate over all entities belonging to a media device, drivers can
> > use the +media_device_for_each_entity macro, defined in
> > include/media/media-device.h. +
> > + struct media_entity *entity;
> > +
> > + media_device_for_each_entity(entity, mdev) {
> > + /* entity will point to each entity in turn */
> > + ...
> > + }
> > +
> > +Drivers might also need to iterate over all entities in a graph that can
> > be +reached only through active links starting at a given entity. The
> > media +framework provides a depth-first graph traversal API for that
> > purpose. +
> > +Note that graphs with cycles (whether directed or undirected) are *NOT*
> > +supported by the graph traversal API.
>
> Please document that a maximum depth exists to prevent loops, currently
> defined as 16 (MEDIA_ENTITY_ENUM_MAX_DEPTH).
Good idea, will do.
--
Regards,
Laurent Pinchart
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