diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-24 09:50:13 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-24 09:50:13 -0700 |
commit | 76d21c563569bcea6bc67d65cc2c460cff643058 (patch) | |
tree | 4dd2c9846ea7838077099646418978e354df1680 /Documentation/DocBook/v4l/media-controller.xml | |
parent | 6e50e9f9f4a8277b4d76de417ca77cf3921bd524 (diff) | |
parent | 472af2b05bdefcaee7e754e22cbf131110017ad6 (diff) |
Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
* 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (442 commits)
[media] videobuf2-dma-contig: make cookie() return a pointer to dma_addr_t
[media] sh_mobile_ceu_camera: Do not call vb2's mem_ops directly
[media] V4L: soc-camera: explicitly require V4L2_BUF_TYPE_VIDEO_CAPTURE
[media] v4l: soc-camera: Store negotiated buffer settings
[media] rc: interim support for 32-bit NEC-ish scancodes
[media] mceusb: topseed 0x0011 needs gen3 init for tx to work
[media] lirc_zilog: error out if buffer read bytes != chunk size
[media] lirc: silence some compile warnings
[media] hdpvr: use same polling interval as other OS
[media] ir-kbd-i2c: pass device code w/key in hauppauge case
[media] rc/keymaps: Remove the obsolete rc-rc5-tv keymap
[media] remove the old RC_MAP_HAUPPAUGE_NEW RC map
[media] rc/keymaps: Rename Hauppauge table as rc-hauppauge
[media] rc-rc5-hauppauge-new: Fix Hauppauge Grey mapping
[media] rc-rc5-hauppauge-new: Add support for the old Black RC
[media] rc-rc5-hauppauge-new: Add the old control to the table
[media] rc-winfast: Fix the keycode tables
[media] a800: Fix a few wrong IR key assignments
[media] opera1: Use multimedia keys instead of an app-specific mapping
[media] dw2102: Use multimedia keys instead of an app-specific mapping
...
Fix up trivial conflicts (remove/modify and some real conflicts) in:
arch/arm/mach-omap2/devices.c
drivers/staging/Kconfig
drivers/staging/Makefile
drivers/staging/dabusb/dabusb.c
drivers/staging/dabusb/dabusb.h
drivers/staging/easycap/easycap_ioctl.c
drivers/staging/usbvideo/usbvideo.c
drivers/staging/usbvideo/vicam.c
Diffstat (limited to 'Documentation/DocBook/v4l/media-controller.xml')
-rw-r--r-- | Documentation/DocBook/v4l/media-controller.xml | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/media-controller.xml b/Documentation/DocBook/v4l/media-controller.xml new file mode 100644 index 00000000000..2dc25e1d408 --- /dev/null +++ b/Documentation/DocBook/v4l/media-controller.xml @@ -0,0 +1,89 @@ +<partinfo> + <authorgroup> + <author> + <firstname>Laurent</firstname> + <surname>Pinchart</surname> + <affiliation><address><email>laurent.pinchart@ideasonboard.com</email></address></affiliation> + <contrib>Initial version.</contrib> + </author> + </authorgroup> + <copyright> + <year>2010</year> + <holder>Laurent Pinchart</holder> + </copyright> + + <revhistory> + <!-- Put document revisions here, newest first. --> + <revision> + <revnumber>1.0.0</revnumber> + <date>2010-11-10</date> + <authorinitials>lp</authorinitials> + <revremark>Initial revision</revremark> + </revision> + </revhistory> +</partinfo> + +<title>Media Controller API</title> + +<chapter id="media_controller"> + <title>Media Controller</title> + + <section id="media-controller-intro"> + <title>Introduction</title> + <para>Media devices increasingly handle multiple related functions. Many USB + cameras include microphones, video capture hardware can also output video, + or SoC camera interfaces also perform memory-to-memory operations similar to + video codecs.</para> + <para>Independent functions, even when implemented in the same hardware, can + be modelled as separate devices. A USB camera with a microphone will be + presented to userspace applications as V4L2 and ALSA capture devices. The + devices' relationships (when using a webcam, end-users shouldn't have to + manually select the associated USB microphone), while not made available + directly to applications by the drivers, can usually be retrieved from + sysfs.</para> + <para>With more and more advanced SoC devices being introduced, the current + approach will not scale. Device topologies are getting increasingly complex + and can't always be represented by a tree structure. Hardware blocks are + shared between different functions, creating dependencies between seemingly + unrelated devices.</para> + <para>Kernel abstraction APIs such as V4L2 and ALSA provide means for + applications to access hardware parameters. As newer hardware expose an + increasingly high number of those parameters, drivers need to guess what + applications really require based on limited information, thereby + implementing policies that belong to userspace.</para> + <para>The media controller API aims at solving those problems.</para> + </section> + + <section id="media-controller-model"> + <title>Media device model</title> + <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 + devices are modelled as an oriented graph of building blocks called entities + connected through pads.</para> + <para>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.</para> + <para>A pad is a 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> + <para>A 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.</para> + </section> +</chapter> + +<appendix id="media-user-func"> + <title>Function Reference</title> + <!-- Keep this alphabetically sorted. --> + &sub-media-open; + &sub-media-close; + &sub-media-ioctl; + <!-- All ioctls go here. --> + &sub-media-ioc-device-info; + &sub-media-ioc-enum-entities; + &sub-media-ioc-enum-links; + &sub-media-ioc-setup-link; +</appendix> |