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diff --git a/Documentation/media/uapi/mediactl/media-controller-model.rst b/Documentation/media/uapi/mediactl/media-controller-model.rst new file mode 100644 index 000000000..558273cf9 --- /dev/null +++ b/Documentation/media/uapi/mediactl/media-controller-model.rst @@ -0,0 +1,35 @@ +.. -*- 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. |