Merge tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull media updates from Mauro Carvalho Chehab:

 - Media documentation is now split into admin-guide, driver-api and
   userspace-api books (a longstanding request from Jon);

 - The media Kconfig was reorganized, in order to make easier to select
   drivers and their dependencies;

 - The testing drivers now has a separate directory;

 - added a new driver for Rockchip Video Decoder IP;

 - The atomisp staging driver was resurrected. It is meant to work with
   4 generations of cameras on Atom-based laptops, tablets and cell
   phones. So, it seems worth investing time to cleanup this driver and
   making it in good shape.

 - Added some V4L2 core ancillary routines to help with h264 codecs;

 - Added an ov2740 image sensor driver;

 - The si2157 gained support for Analog TV, which, in turn, added
   support for some cx231xx and cx23885 boards to also support analog
   standards;

 - Added some V4L2 controls (V4L2_CID_CAMERA_ORIENTATION and
   V4L2_CID_CAMERA_SENSOR_ROTATION) to help identifying where the camera
   is located at the device;

 - VIDIOC_ENUM_FMT was extended to support MC-centric devices;

 - Lots of drivers improvements and cleanups.

* tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (503 commits)
  media: Documentation: media: Refer to mbus format documentation from CSI-2 docs
  media: s5k5baf: Replace zero-length array with flexible-array
  media: i2c: imx219: Drop <linux/clk-provider.h> and <linux/clkdev.h>
  media: i2c: Add ov2740 image sensor driver
  media: ov8856: Implement sensor module revision identification
  media: ov8856: Add devicetree support
  media: dt-bindings: ov8856: Document YAML bindings
  media: dvb-usb: Add Cinergy S2 PCIe Dual Port support
  media: dvbdev: Fix tuner->demod media controller link
  media: dt-bindings: phy: phy-rockchip-dphy-rx0: move rockchip dphy rx0 bindings out of staging
  media: staging: dt-bindings: phy-rockchip-dphy-rx0: remove non-used reg property
  media: atomisp: unify the version for isp2401 a0 and b0 versions
  media: atomisp: update TODO with the current data
  media: atomisp: adjust some code at sh_css that could be broken
  media: atomisp: don't produce errs for ignored IRQs
  media: atomisp: print IRQ when debugging
  media: atomisp: isp_mmu: don't use kmem_cache
  media: atomisp: add a notice about possible leak resources
  media: atomisp: disable the dynamic and reserved pools
  media: atomisp: turn on camera before setting it
  ...

1 files changed, 40 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/mediactl/media-controller-intro.rst b/Documentation/userspace-api/media/mediactl/media-controller-intro.rst
new file mode 100644
index 000000000000..1d06ea4c4d09
--- /dev/null
+++ b/Documentation/userspace-api/media/mediactl/media-controller-intro.rst
@@ -0,0 +1,40 @@
+.. 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-intro:
+
+Introduction
+============
+
+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.
+
+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.
+
+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.
+
+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.
+
+The media controller API aims at solving those problems.