60c2820d0f
The name of the subsystem is "media", and not "linux_tv". Also, as we plan to add other stuff there in the future, let's rename also the media uAPI book to media_uapi, to make it clearer. No functional changes. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
35 lines
1.5 KiB
ReStructuredText
35 lines
1.5 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
|
|
|
|
.. _media-controller-model:
|
|
|
|
Media device model
|
|
==================
|
|
|
|
Discovering a device internal topology, and configuring it at runtime,
|
|
is one of the goals of the media controller API. To achieve this,
|
|
hardware devices and Linux Kernel interfaces are modelled as graph
|
|
objects on an oriented graph. The object types that constitute the graph
|
|
are:
|
|
|
|
- An **entity** is a basic media hardware or software 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.
|
|
|
|
- An **interface** is a graph representation of a Linux Kernel
|
|
userspace API interface, like a device node or a sysfs file that
|
|
controls one or more entities in the graph.
|
|
|
|
- A **pad** 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.
|
|
|
|
- A **data 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.
|
|
|
|
- An **interface link** is a point-to-point bidirectional control
|
|
connection between a Linux Kernel interface and an entity.
|