media_create_pad_links
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Name

media_create_pad_links — creates a link between two entities.

Synopsis

int media_create_pad_links (const struct media_device * mdev,
 const u32 source_function,
 struct media_entity * source,
 const u16 source_pad,
 const u32 sink_function,
 struct media_entity * sink,
 const u16 sink_pad,
 u32 flags,
 const bool allow_both_undefined);
 

Arguments

mdev

Pointer to the media_device that contains the object

source_function

Function of the source entities. Used only if source is NULL.

source

pointer to media_entity of the source pad. If NULL, it will use all entities that matches the sink_function.

source_pad

number of the source pad in the pads array

sink_function

Function of the sink entities. Used only if sink is NULL.

sink

pointer to media_entity of the sink pad. If NULL, it will use all entities that matches the sink_function.

sink_pad

number of the sink pad in the pads array.

flags

Link flags, as defined in include/uapi/linux/media.h.

allow_both_undefined

if true, then both source and sink can be NULL. In such case, it will create a crossbar between all entities that matches source_function to all entities that matches sink_function. If false, it will return 0 and won't create any link if both source and sink are NULL.

Valid values for flags

A MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be used to transfer media data. If multiple links are created and this flag is passed as an argument, only the first created link will have this flag.

A MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't be modified at runtime. If MEDIA_LNK_FL_IMMUTABLE is set, then MEDIA_LNK_FL_ENABLED must also be set since an immutable link is always enabled.

It is common for some devices to have multiple source and/or sink entities of the same type that should be linked. While media_create_pad_link creates link by link, this function is meant to allow 1:n, n:1 and even cross-bar (n:n) links.

NOTE

Before calling this function, media_entity_pads_init and media_device_register_entity should be called previously for the entities to be linked.

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