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Commit b7870d69 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

[media] DocBook: MC: add the concept of interfaces 



The Media Controller next generation patches added a new graph
element type: interfaces. It also allows links between interfaces
and entities. Update the docbook to reflect that.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent fdc40b5e

Documentation/DocBook/media/v4l/media-controller.xml

+26 −14
Original line number Original line Diff line number Diff line
@@ -58,20 +58,32 @@ 
    <title>Media device model</title>

    <title>Media device model</title>

    <para>Discovering a device internal topology, and configuring it at runtime,

    <para>Discovering a device internal topology, and configuring it at runtime,

    is one of the goals of the media controller API. To achieve this, hardware

    is one of the goals of the media controller API. To achieve this, hardware

    devices are modelled as an oriented graph of building blocks called entities

    devices and Linux Kernel interfaces are modelled as graph objects on

    connected through pads.</para>

    an oriented graph. The object types that constitute the graph are:</para>

    <para>An entity is a basic media hardware or software building block. It can

    <itemizedlist>

    correspond to a large variety of logical blocks such as physical hardware

    <listitem><para>An <emphasis role="bold">entity</emphasis>

    devices (CMOS sensor for instance), logical hardware devices (a building

    is a basic media hardware or software building block. It can correspond to

    block in a System-on-Chip image processing pipeline), DMA channels or

    a large variety of logical blocks such as physical hardware devices

    physical connectors.</para>

    (CMOS sensor for instance), logical hardware devices (a building block in

    <para>A pad is a connection endpoint through which an entity can interact

    a System-on-Chip image processing pipeline), DMA channels or physical

    with other entities. Data (not restricted to video) produced by an entity

    connectors.</para></listitem>

    flows from the entity's output to one or more entity inputs. Pads should not

    <listitem><para>An <emphasis role="bold">interface</emphasis>

    be confused with physical pins at chip boundaries.</para>

    is a graph representation of a Linux Kernel userspace API interface,

    <para>A link is a point-to-point oriented connection between two pads,

    like a device node or a sysfs file that controls one or more entities

    either on the same entity or on different entities. Data flows from a source

    in the graph.</para></listitem>

    pad to a sink pad.</para>

    <listitem><para>A <emphasis role="bold">pad</emphasis>

    is a data 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.</para></listitem>

    <listitem><para>A <emphasis role="bold">data link</emphasis>

    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.</para></listitem>

    <listitem><para>An <emphasis role="bold">interface link</emphasis>

    is a point-to-point bidirectional control connection between a Linux

    Kernel interface and an entity.m</para></listitem>

    </itemizedlist>

  </section>

  </section>

</chapter>

</chapter>