Merge tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull media documentation updates from Mauro Carvalho Chehab:
 "This patch series does the conversion of all media documentation stuff
  to Restrutured Text markup format and add them to the
  Documentation/index.rst file.

  The media documentation was grouped into 4 books:

    - media uAPI
    - media kAPI
    - V4L driver-specific documentation
    - DVB driver-specific documentation

  It also contains several documentation improvements and one fixup
  patch for a core issue with cropcap.

  PS.  After this patch series, the media DocBook is deprecated and
  should be removed.  I'll add such patch on a future pull request"

* tag 'media/v4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (322 commits)
  [media] cx23885-cardlist.rst: add a new card
  [media] doc-rst: add some needed escape codes
  [media] doc-rst: kapi: use :c:func: instead of :cpp:func
  doc-rst: kernel-doc: fix a change introduced by mistake
  [media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops
  [media] dvb_ringbuffer.h: some documentation improvements
  [media] v4l2-ctrls.h: fully document the header file
  [media] doc-rst: Fix some typedef ugly warnings
  [media] doc-rst: reorganize the kAPI v4l2 chapters
  [media] rename v4l2-framework.rst to v4l2-intro.rst
  [media] move V4L2 clocks to a separate .rst file
  [media] v4l2-fh.rst: add cross references and markups
  [media] v4l2-fh.rst: add fh contents from v4l2-framework.rst
  [media] v4l2-fh.h: add documentation for it
  [media] v4l2-event.rst: add cross-references and markups
  [media] v4l2-event.h: document all functions
  [media] v4l2-event.rst: add text from v4l2-framework.rst
  [media] v4l2-framework.rst: remove videobuf quick chapter
  [media] v4l2-dev: add cross-references and improve markup
  [media] doc-rst: move v4l2-dev doc to a separate file
  ...

1 files changed, 95 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/audio.rst b/Documentation/media/uapi/v4l/audio.rst
new file mode 100644
index 000000000000..4dd11345866c
--- /dev/null
+++ b/Documentation/media/uapi/v4l/audio.rst
@@ -0,0 +1,95 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _audio:
+
+************************
+Audio Inputs and Outputs
+************************
+
+Audio inputs and outputs are physical connectors of a device. Video
+capture devices have inputs, output devices have outputs, zero or more
+each. Radio devices have no audio inputs or outputs. They have exactly
+one tuner which in fact *is* an audio source, but this API associates
+tuners with video inputs or outputs only, and radio devices have none of
+these. [#f1]_ A connector on a TV card to loop back the received audio
+signal to a sound card is not considered an audio output.
+
+Audio and video inputs and outputs are associated. Selecting a video
+source also selects an audio source. This is most evident when the video
+and audio source is a tuner. Further audio connectors can combine with
+more than one video input or output. Assumed two composite video inputs
+and two audio inputs exist, there may be up to four valid combinations.
+The relation of video and audio connectors is defined in the
+``audioset`` field of the respective struct
+:ref:`v4l2_input <v4l2-input>` or struct
+:ref:`v4l2_output <v4l2-output>`, where each bit represents the index
+number, starting at zero, of one audio input or output.
+
+To learn about the number and attributes of the available inputs and
+outputs applications can enumerate them with the
+:ref:`VIDIOC_ENUMAUDIO` and
+:ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>` ioctl, respectively.
+The struct :ref:`v4l2_audio <v4l2-audio>` returned by the
+:ref:`VIDIOC_ENUMAUDIO` ioctl also contains signal
+:status information applicable when the current audio input is queried.
+
+The :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` and
+:ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDOUT>` ioctls report the current
+audio input and output, respectively.
+
+.. note:: Note that, unlike :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
+   :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` these ioctls return a
+   structure as :ref:`VIDIOC_ENUMAUDIO` and
+   :ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>` do, not just an index.
+
+To select an audio input and change its properties applications call the
+:ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl. To select an audio
+output (which presently has no changeable properties) applications call
+the :ref:`VIDIOC_S_AUDOUT <VIDIOC_G_AUDOUT>` ioctl.
+
+Drivers must implement all audio input ioctls when the device has
+multiple selectable audio inputs, all audio output ioctls when the
+device has multiple selectable audio outputs. When the device has any
+audio inputs or outputs the driver must set the ``V4L2_CAP_AUDIO`` flag
+in the struct :ref:`v4l2_capability <v4l2-capability>` returned by
+the :ref:`VIDIOC_QUERYCAP` ioctl.
+
+
+Example: Information about the current audio input
+==================================================
+
+.. code-block:: c
+
+    struct v4l2_audio audio;
+
+    memset(&audio, 0, sizeof(audio));
+
+    if (-1 == ioctl(fd, VIDIOC_G_AUDIO, &audio)) {
+	perror("VIDIOC_G_AUDIO");
+	exit(EXIT_FAILURE);
+    }
+
+    printf("Current input: %s\\n", audio.name);
+
+
+Example: Switching to the first audio input
+===========================================
+
+.. code-block:: c
+
+    struct v4l2_audio audio;
+
+    memset(&audio, 0, sizeof(audio)); /* clear audio.mode, audio.reserved */
+
+    audio.index = 0;
+
+    if (-1 == ioctl(fd, VIDIOC_S_AUDIO, &audio)) {
+	perror("VIDIOC_S_AUDIO");
+	exit(EXIT_FAILURE);
+    }
+
+.. [#f1]
+   Actually struct :ref:`v4l2_audio <v4l2-audio>` ought to have a
+   ``tuner`` field like struct :ref:`v4l2_input <v4l2-input>`, not
+   only making the API more consistent but also permitting radio devices
+   with multiple tuners.