Re: [RFC/PATCH v3 03/10] media: Entities, pads and links

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Hi Hans,

On Sunday 01 August 2010 13:32:50 Hans Verkuil wrote:
> On Thursday 29 July 2010 18:06:36 Laurent Pinchart wrote:

<snip>

> > diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> > new file mode 100644
> > index 0000000..37a25bf
> > --- /dev/null
> > +++ b/include/media/media-entity.h
> > @@ -0,0 +1,85 @@
> > +#ifndef _MEDIA_ENTITY_H
> > +#define _MEDIA_ENTITY_H
> > +
> > +#include <linux/list.h>
> > +
> > +#define MEDIA_ENTITY_TYPE_NODE			(1 << 16)
> 
> I agree with Sakari that '16' should be a define.

Will do.

> > +#define MEDIA_ENTITY_TYPE_NODE_V4L		(MEDIA_ENTITY_TYPE_NODE + 1)
> > +#define MEDIA_ENTITY_TYPE_NODE_FB		(MEDIA_ENTITY_TYPE_NODE + 2)
> > +#define MEDIA_ENTITY_TYPE_NODE_ALSA		(MEDIA_ENTITY_TYPE_NODE + 3)
> > +#define MEDIA_ENTITY_TYPE_NODE_DVB		(MEDIA_ENTITY_TYPE_NODE + 4)
> > +
> > +#define MEDIA_ENTITY_TYPE_SUBDEV		(2 << 16)
> > +#define MEDIA_ENTITY_TYPE_SUBDEV_VID_DECODER	(MEDIA_ENTITY_TYPE_SUBDEV +
> > 1)
> > +#define MEDIA_ENTITY_TYPE_SUBDEV_VID_ENCODER	(MEDIA_ENTITY_TYPE_SUBDEV +
> > 2)
> > +#define MEDIA_ENTITY_TYPE_SUBDEV_MISC		(MEDIA_ENTITY_TYPE_SUBDEV + 3) 
+
> > +#define MEDIA_LINK_FLAG_ACTIVE			(1 << 0)
> > +#define MEDIA_LINK_FLAG_IMMUTABLE		(1 << 1)
> > +
> > +#define MEDIA_PAD_FLAG_INPUT			(1 << 0)
> > +#define MEDIA_PAD_FLAG_OUTPUT			(1 << 1)
> > +
> > +struct media_link {
> > +	struct media_pad *source;	/* Source pad */
> > +	struct media_pad *sink;		/* Sink pad  */
> > +	struct media_link *other;	/* Link in the reverse direction */
> 
> Why not rename 'other' to 'back' or 'backlink'? 'other' is not a good name
> IMHO.

For forward links other is the backlink, but for backlinks other is the 
forward link. I'll rename it to reverse.

> > +	unsigned long flags;		/* Link flags (MEDIA_LINK_FLAG_*) */
> > +};
> > +
> > +struct media_pad {
> > +	struct media_entity *entity;	/* Entity this pad belongs to */
> > +	u16 index;			/* Pad index in the entity pads array */
> > +	unsigned long flags;		/* Pad flags (MEDIA_PAD_FLAG_*) */
> > +};
> > +
> > +struct media_entity {
> > +	struct list_head list;
> > +	struct media_device *parent;	/* Media device this entity belongs to*/
> > +	u32 id;				/* Entity ID, unique in the parent media
> > +					 * device context */
> > +	const char *name;		/* Entity name */
> > +	u32 type;			/* Entity type (MEDIA_ENTITY_TYPE_*) */
> > +
> > +	u8 num_pads;			/* Number of input and output pads */
> > +	u8 num_links;			/* Number of existing links, both active
> > +					 * and inactive */
> > +	u8 num_backlinks;		/* Number of backlinks */
> > +	u8 max_links;			/* Maximum number of links */
> > +
> > +	struct media_pad *pads;		/* Pads array (num_pads elements) */
> > +	struct media_link *links;	/* Links array (max_links elements)*/
> > +
> > +	union {
> > +		/* Node specifications */
> > +		struct {
> > +			u32 major;
> > +			u32 minor;
> > +		} v4l;
> > +		struct {
> > +			u32 major;
> > +			u32 minor;
> > +		} fb;
> > +		int alsa;
> > +		int dvb;
> > +
> > +		/* Sub-device specifications */
> > +		/* Nothing needed yet */
> > +	};
> > +};
> > +
> > +#define MEDIA_ENTITY_TYPE_MASK		0xffff0000
> > +#define MEDIA_ENTITY_SUBTYPE_MASK	0x0000ffff
> > +
> > +#define media_entity_type(entity) \
> > +	((entity)->type & MEDIA_ENTITY_TYPE_MASK)
> > +#define media_entity_subtype(entity) \
> > +	((entity)->type & MEDIA_ENTITY_SUBTYPE_MASK)
> 
> Make these inline functions to ensure correct typechecking.

OK.

> Since bit 31 of the entity ID is reserved for MEDIA_ENTITY_ID_FLAG_NEXT you
> probably should change the TYPE_MASK to 0x7fff0000. Actually, I would
> change the type mask to 0x00ff0000, that way all top 8 bits are available
> for the future.

Agreed.

> > +
> > +int media_entity_init(struct media_entity *entity, u8 num_pads,
> > +		struct media_pad *pads, u8 extra_links);
> > +void media_entity_cleanup(struct media_entity *entity);
> > +int media_entity_create_link(struct media_entity *source, u8 source_pad,
> > +		struct media_entity *sink, u8 sink_pad, u32 flags);
> > +
> > +#endif

-- 
Regards,

Laurent Pinchart
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