diff options
Diffstat (limited to 'Documentation/userspace-api/media/mediactl/media-controller-model.rst')
| -rw-r--r-- | Documentation/userspace-api/media/mediactl/media-controller-model.rst | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/mediactl/media-controller-model.rst b/Documentation/userspace-api/media/mediactl/media-controller-model.rst new file mode 100644 index 000000000000..865e73d934d6 --- /dev/null +++ b/Documentation/userspace-api/media/mediactl/media-controller-model.rst @@ -0,0 +1,42 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + +.. _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. |