Em Mon, 31 Aug 2015 13:31:32 +0200
Hans Verkuil <hverk...@xs4all.nl> escreveu:

> On 08/30/2015 05:06 AM, Mauro Carvalho Chehab wrote:
> > As we'll be removing entity subtypes from the Kernel, we need
> > to provide a way for drivers and core to check if a given
> > entity is represented by a V4L2 subdev or if it is an V4L2
> > I/O entity (typically with DMA).
> 
> This needs more discussion. The plan (as I understand it) is to have 
> properties
> that describe the entity's functionalities.
> 
> The existing entity subtypes will exist only as backwards compat types, but in
> the future properties should be used to describe the functionalities.
> 
> This raises the question if we shouldn't use MEDIA_ENT_T_V4L2_SUBDEV to tell
> userspace that this is a subdev-controlled entity, and let userspace look at
> the properties to figure out what it is exactly?
> 
> It could be that this is a transitional patch, and this will be fixed later.
> If so, this should be mentioned in the commit message.

There are several different issues here:

1) drivers should not rely on type/subtype at MEDIA_ENT_T_*, as we need
   to get rid of it, as this got deprecated;

2) Keep backward compatibility.

3) the addition of properties;

The next patch on this series addresses (1) and (2), and this change is
needed for them.

We can't tell if this is a transitional patch or not, as we don't have
yet any idea about how (3) will be added. Maybe it will preserve
entity->type. Maybe it will convert it into an array. Maybe it would
do something different.

In any case, whatever the property patches will be doing, after this
patch, it will need to touch only at the implementation of the two
macros, not needing to touch at the drivers again.

What I can do is to tell at the description that this patch is in
preparation for the removal of media type/subtype concept that will 
happen on the next patches, but this is what's described there already
at:
        "As we'll be removing entity subtypes from the Kernel,"

Perhaps I should let it clearer there.

Regards,
Mauro

> 
> Regards,
> 
>       Hans
> 
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mche...@osg.samsung.com>
> > 
> > diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> > index e7b20bdc735d..b0cfbc0dffc7 100644
> > --- a/include/media/media-entity.h
> > +++ b/include/media/media-entity.h
> > @@ -220,6 +220,39 @@ static inline u32 media_gobj_gen_id(enum 
> > media_gobj_type type, u32 local_id)
> >     return id;
> >  }
> >  
> > +static inline bool is_media_entity_v4l2_io(struct media_entity *entity)
> > +{
> > +   if (!entity)
> > +           return false;
> > +
> > +   switch (entity->type) {
> > +   case MEDIA_ENT_T_V4L2_VIDEO:
> > +   case MEDIA_ENT_T_V4L2_VBI:
> > +   case MEDIA_ENT_T_V4L2_SWRADIO:
> > +           return true;
> > +   default:
> > +           return false;
> > +   }
> > +}
> > +
> > +static inline bool is_media_entity_v4l2_subdev(struct media_entity *entity)
> > +{
> > +   if (!entity)
> > +           return false;
> > +
> > +   switch (entity->type) {
> > +   case MEDIA_ENT_T_V4L2_SUBDEV_SENSOR:
> > +   case MEDIA_ENT_T_V4L2_SUBDEV_FLASH:
> > +   case MEDIA_ENT_T_V4L2_SUBDEV_LENS:
> > +   case MEDIA_ENT_T_V4L2_SUBDEV_DECODER:
> > +   case MEDIA_ENT_T_V4L2_SUBDEV_TUNER:
> > +           return true;
> > +
> > +   default:
> > +           return false;
> > +   }
> > +}
> > +
> >  #define MEDIA_ENTITY_ENUM_MAX_DEPTH        16
> >  #define MEDIA_ENTITY_ENUM_MAX_ID   64
> >  
> > 
> 
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