Re: [PATCH RFC v5 2/8] [media] media: add a common struct to be embed on media graph objects

Mauro Carvalho Chehab
2015-08-19T09:19:40Z

Em Wed, 19 Aug 2015 10:17:46 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> On 08/18/2015 10:04 PM, Mauro Carvalho Chehab wrote:
> > Due to the MC API proposed changes, we'll need to have an unique
> > object ID for all graph objects, and have some shared fields
> > that will be common on all media graph objects.
> >
> > Right now, the only common object is the object ID, but other
> > fields will be added later on.
> >
> > Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> >
> > diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> > index cb0ac4e0dfa5..4834172bf6f8 100644
> > --- a/drivers/media/media-entity.c
> > +++ b/drivers/media/media-entity.c
> > @@ -27,6 +27,38 @@
> > #include <media/media-device.h>
> >
> > /**
> > + * media_gobj_init - Initialize a graph object
> > + *
> > + * @mdev: Pointer to the media_device that contains the object
> > + * @type: Type of the object
> > + * @gobj: Pointer to the object
> > + *
> > + * This routine initializes the embedded struct media_gobj inside a
> > + * media graph object. It is called automatically if media_*_create()
> > + * calls are used. However, if the object (entity, link, pad, interface)
> > + * is embedded on some other object, this function should be called before
> > + * registering the object at the media controller.
> > + */
> > +void media_gobj_init(struct media_device *mdev,
> > + enum media_gobj_type type,
> > + struct media_gobj *gobj)
> > +{
> > + /* For now, nothing to do */
> > +}
> > +
> > +/**
> > + * media_gobj_remove - Stop using a graph object on a media device
> > + *
> > + * @graph_obj: Pointer to the object
> > + *
> > + * This should be called at media_device_unregister_*() routines
> > + */
> > +void media_gobj_remove(struct media_gobj *gobj)
> > +{
> > + /* For now, nothing to do */
> > +}
> > +
> > +/**
> > * media_entity_init - Initialize a media entity
> > *
> > * @num_pads: Total number of sink and source pads.
> > diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> > index 0a66fc225559..762593c7424f 100644
> > --- a/include/media/media-entity.h
> > +++ b/include/media/media-entity.h
> > @@ -28,6 +28,37 @@
> > #include <linux/list.h>
> > #include <linux/media.h>
> >
> > +/* Enums used internally at the media controller to represent graphs */
> > +
> > +/**
> > + * enum media_gobj_type - type of a graph element
> > + *
> > + */
> > +enum media_gobj_type {
> > + /* FIXME: add the types here, as we embed media_gobj */
> > + MEDIA_GRAPH_NONE
> > +};
> > +
> > +#define BITS_PER_TYPE 8
> > +#define BITS_PER_LOCAL_ID (32 - BITS_PER_TYPE)
>
> I think that these two defines should be prefixed with MEDIA_.
> They are a bit too generic for a header that's going to be used in lots
> of drivers.
> I also think that the local ID mask should be a define as well:
>
> #define MEDIA_LOCAL_ID_MASK GENMASK(BITS_PER_LOCAL_ID - 1, 0)
>
> That will make the code where this mask is used a bit more readable.

Ok, I'll change them.

>
> > +
> > +/* Structs to represent the objects that belong to a media graph */
> > +
> > +/**
> > + * struct media_gobj - Define a graph object.
> > + *
> > + * @id: Non-zero object ID identifier. The ID should be unique
> > + * inside a media_device, as it is composed by
> > + * BITS_PER_TYPE to store the type plus BITS_PER_LOCAL_ID
> > + * to store a per-type ID (called as "local ID").
> > + *
> > + * All elements on the media graph should have this struct embedded
> > + */
> > +struct media_gobj {
> > + u32 id;
> > +};
> > +
> > +
> > struct media_pipeline {
> > };
> >
> > @@ -118,6 +149,26 @@ static inline u32 media_entity_id(struct media_entity *entity)
> > return entity->id;
> > }
> >
> > +static inline enum media_gobj_type media_type(struct media_gobj *gobj)
> > +{
> > + return gobj->id >> BITS_PER_LOCAL_ID;
> > +}
> > +
> > +static inline u32 media_localid(struct media_gobj *gobj)
> > +{
> > + return gobj->id & GENMASK(BITS_PER_LOCAL_ID - 1, 0);
> > +}
> > +
> > +static inline u32 media_gobj_gen_id(enum media_gobj_type type, u32 local_id)
> > +{
> > + u32 id;
> > +
> > + id = type << BITS_PER_LOCAL_ID;
> > + id |= GENMASK(BITS_PER_LOCAL_ID - 1, 0) & local_id;
>
> I'd swap this: id |= local_id & MEDIA_LOCAL_ID_MASK;
>
> It feels more natural that way and it is consistent with media_localid() above.

Ok.

>
> Regards,
>
> Hans
>
> > +
> > + return id;
> > +}
> > +
> > #define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
> > #define MEDIA_ENTITY_ENUM_MAX_ID 64
> >
> > @@ -131,6 +182,14 @@ struct media_entity_graph {
> > int top;
> > };
> >
> > +#define gobj_to_entity(gobj) \
> > + container_of(gobj, struct media_entity, graph_obj)
> > +
> > +void media_gobj_init(struct media_device *mdev,
> > + enum media_gobj_type type,
> > + struct media_gobj *gobj);
> > +void media_gobj_remove(struct media_gobj *gobj);
> > +
> > int media_entity_init(struct media_entity *entity, u16 num_pads,
> > struct media_pad *pads);
> > void media_entity_cleanup(struct media_entity *entity);
> >
>