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, 91 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/func-write.rst b/Documentation/userspace-api/media/v4l/func-write.rst
new file mode 100644
index 000000000000..fb1955f70f0f
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/func-write.rst
@@ -0,0 +1,91 @@
+.. 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
+
+.. _func-write:
+
+************
+V4L2 write()
+************
+
+Name
+====
+
+v4l2-write - Write to a V4L2 device
+
+
+Synopsis
+========
+
+.. code-block:: c
+
+    #include <unistd.h>
+
+
+.. c:function:: ssize_t write( int fd, void *buf, size_t count )
+    :name: v4l2-write
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``buf``
+     Buffer with data to be written
+
+``count``
+    Number of bytes at the buffer
+
+Description
+===========
+
+:ref:`write() <func-write>` writes up to ``count`` bytes to the device
+referenced by the file descriptor ``fd`` from the buffer starting at
+``buf``. When the hardware outputs are not active yet, this function
+enables them. When ``count`` is zero, :ref:`write() <func-write>` returns 0
+without any other effect.
+
+When the application does not provide more data in time, the previous
+video frame, raw VBI image, sliced VPS or WSS data is displayed again.
+Sliced Teletext or Closed Caption data is not repeated, the driver
+inserts a blank line instead.
+
+
+Return Value
+============
+
+On success, the number of bytes written are returned. Zero indicates
+nothing was written. On error, -1 is returned, and the ``errno``
+variable is set appropriately. In this case the next write will start at
+the beginning of a new frame. Possible error codes are:
+
+EAGAIN
+    Non-blocking I/O has been selected using the
+    :ref:`O_NONBLOCK <func-open>` flag and no buffer space was
+    available to write the data immediately.
+
+EBADF
+    ``fd`` is not a valid file descriptor or is not open for writing.
+
+EBUSY
+    The driver does not support multiple write streams and the device is
+    already in use.
+
+EFAULT
+    ``buf`` references an inaccessible memory area.
+
+EINTR
+    The call was interrupted by a signal before any data was written.
+
+EIO
+    I/O error. This indicates some hardware problem.
+
+EINVAL
+    The :ref:`write() <func-write>` function is not supported by this driver,
+    not on this device, or generally not on this type of device.