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  1. 22 Mar, 2011 5 commits
    • Laurent Pinchart's avatar
      [media] media: Entity use count · 503c3d82
      Laurent Pinchart authored 
      Due to the wide differences between drivers regarding power management
needs, the media controller does not implement power management.
However, the media_entity structure includes a use_count field that
media drivers can use to track the number of users of every entity for
power management needs.

The use_count field is owned by media drivers and must not be touched by
entity drivers. Access to the field must be protected by the media
device graph_mutex lock.
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      503c3d82
    • Sakari Ailus's avatar
      [media] media: Entity graph traversal · a5ccc48a
      Sakari Ailus authored 
      Add media entity graph traversal. The traversal follows enabled 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: default avatarSakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarVimarsh Zutshi <vimarsh.zutshi@gmail.com>
Acked-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      a5ccc48a
    • Laurent Pinchart's avatar
      [media] media: Entities, pads and links · 53e269c1
      Laurent Pinchart authored 
      As video hardware pipelines become increasingly complex and
configurable, the current hardware description through v4l2 subdevices
reaches its limits. In addition to enumerating and configuring
subdevices, video camera drivers need a way to discover and modify at
runtime how those subdevices are connected. This is done through new
elements called entities, pads and links.

An entity is a basic media hardware building block. It can correspond to
a large variety of logical blocks such as physical hardware devices
(CMOS sensor for instance), logical hardware devices (a building block
in a System-on-Chip image processing pipeline), DMA channels or physical
connectors.

A pad is a connection endpoint through which an entity can interact with
other entities. Data (not restricted to video) produced by an entity
flows from the entity's output to one or more entity inputs. Pads should
not be confused with physical pins at chip boundaries.

A link is a point-to-point oriented connection between two pads, either
on the same entity or on different entities. Data flows from a source
pad to a sink pad.

Links are stored in the source entity. To make backwards graph walk
faster, a copy of all links is also stored in the sink entity. The copy
is known as a backlink and is only used to help graph traversal.

The entity API is made of three functions:

- media_entity_init() initializes an entity. The caller must provide an
array of pads as well as an estimated number of links. The links array
is allocated dynamically and will be reallocated if it grows beyond the
initial estimate.

- media_entity_cleanup() frees resources allocated for an entity. It
must be called during the cleanup phase after unregistering the entity
and before freeing it.

- media_entity_create_link() creates a link between two entities. An
entry in the link array of each entity is allocated and stores pointers
to source and sink pads.

When a media device is unregistered, all its entities are unregistered
automatically.

The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work.
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@iki.fi>
Acked-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      53e269c1
    • Laurent Pinchart's avatar
      [media] media: Media device · 176fb0d1
      Laurent Pinchart authored 
      The media_device structure abstracts functions common to all kind of
media devices (v4l2, dvb, alsa, ...). It manages media entities and
offers a userspace API to discover and configure the media device
internal topology.
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      176fb0d1
    • Laurent Pinchart's avatar
      [media] media: Media device node support · cf4b9211
      Laurent Pinchart authored 
      The media_devnode structure provides support for registering and
unregistering character devices using a dynamic major number. Reference
counting is handled internally, making device drivers easier to write
without having to solve the open/disconnect race condition issue over
and over again.

The code is based on video/v4l2-dev.c.

[mchehab@redhat.com: Remove linux/smp_lock.h include to not break compilation on bisect]
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      cf4b9211
  3. 21 Mar, 2011 35 commits
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