linux-3.3/Documentation/media-framework.txt

9 ------------
12 Documentation/DocBook/media/v4l/media-controller.xml. This document will focus
13 on the kernel-side implementation of the media framework.
17 ---------------------------
27 in a System-on-Chip image processing pipeline), DMA channels or physical
35 A link is a point-to-point oriented connection between two pads, either
41 ------------
44 include/media/media-device.h. Allocation of the structure is handled by the
46 larger driver-specific structure.
55  - dev must point to the parent device (usually a pci_dev, usb_interface or
58  - model must be filled with the device model name as a NUL-terminated UTF-8
63  - serial is a unique serial number stored as a NUL-terminated ASCII string.
67  - bus_info represents the location of the device in the system as a
68    NUL-terminated ASCII string. For PCI/PCIe devices bus_info must be set to
74  - hw_revision is the hardware device revision in a driver-specific format.
78  - driver_version is formatted with the KERNEL_VERSION macro. The version
83 Upon successful registration a character device named media[0-9]+ is created.
95 ------------------------
97 - Entities
100 include/media/media-entity.h. The structure is usually embedded into a
101 higher-level structure, such as a v4l2_subdev or video_device instance,
111 higher-level standard structures can have some of those fields set by the
112 higher-level framework.
116 pads array in a driver-specific structure, avoiding dynamic allocation.
123 pre-allocates a number of links equal to the number of pads plus an optional
163 entities to the same non-zero value. An entity group serves no purpose in the
171 	- ALSA, VBI and video nodes that carry the same media stream
172 	- lens and flash controllers associated with a sensor
174 - Pads
177 include/media/media-entity.h. Each entity stores its pads in a pads array
179 driver-specific structure.
181 Pads are identified by their entity and their 0-based index in the pads array.
193 - Links
196 include/media/media-entity.h. Each entity stores all links originating at or
199 pre-allocated and grows dynamically as needed.
222 ---------------
227 media_device_for_each_entity macro, defined in include/media/media-device.h.
238 framework provides a depth-first graph traversal API for that purpose.
274 ----------------------------
287 -----------
309 is non-immutable. The operation must either configure the hardware or store
314 the link_setup operation must return -EBUSY and can't implicitly disable the
319 ---------------------------
332 in higher-level pipeline structures and can then access the pipeline through
346 Link configuration will fail with -EBUSY by default if either end of the link is