doc_rst: rename the media Sphinx suff to Documentation/media

The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 171 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/vidioc-subdev-g-fmt.rst b/Documentation/media/uapi/v4l/vidioc-subdev-g-fmt.rst
new file mode 100644
index 000000000000..90e2a6635ebc
--- /dev/null
+++ b/Documentation/media/uapi/v4l/vidioc-subdev-g-fmt.rst
@@ -0,0 +1,171 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _VIDIOC_SUBDEV_G_FMT:
+
+**********************************************
+ioctl VIDIOC_SUBDEV_G_FMT, VIDIOC_SUBDEV_S_FMT
+**********************************************
+
+Name
+====
+
+VIDIOC_SUBDEV_G_FMT - VIDIOC_SUBDEV_S_FMT - Get or set the data format on a subdev pad
+
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_subdev_format *argp )
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+    VIDIOC_SUBDEV_G_FMT, VIDIOC_SUBDEV_S_FMT
+
+``argp``
+
+
+Description
+===========
+
+These ioctls are used to negotiate the frame format at specific subdev
+pads in the image pipeline.
+
+To retrieve the current format applications set the ``pad`` field of a
+struct :ref:`v4l2_subdev_format <v4l2-subdev-format>` to the desired
+pad number as reported by the media API and the ``which`` field to
+``V4L2_SUBDEV_FORMAT_ACTIVE``. When they call the
+``VIDIOC_SUBDEV_G_FMT`` ioctl with a pointer to this structure the
+driver fills the members of the ``format`` field.
+
+To change the current format applications set both the ``pad`` and
+``which`` fields and all members of the ``format`` field. When they call
+the ``VIDIOC_SUBDEV_S_FMT`` ioctl with a pointer to this structure the
+driver verifies the requested format, adjusts it based on the hardware
+capabilities and configures the device. Upon return the struct
+:ref:`v4l2_subdev_format <v4l2-subdev-format>` contains the current
+format as would be returned by a ``VIDIOC_SUBDEV_G_FMT`` call.
+
+Applications can query the device capabilities by setting the ``which``
+to ``V4L2_SUBDEV_FORMAT_TRY``. When set, 'try' formats are not applied
+to the device by the driver, but are changed exactly as active formats
+and stored in the sub-device file handle. Two applications querying the
+same sub-device would thus not interact with each other.
+
+For instance, to try a format at the output pad of a sub-device,
+applications would first set the try format at the sub-device input with
+the ``VIDIOC_SUBDEV_S_FMT`` ioctl. They would then either retrieve the
+default format at the output pad with the ``VIDIOC_SUBDEV_G_FMT`` ioctl,
+or set the desired output pad format with the ``VIDIOC_SUBDEV_S_FMT``
+ioctl and check the returned value.
+
+Try formats do not depend on active formats, but can depend on the
+current links configuration or sub-device controls value. For instance,
+a low-pass noise filter might crop pixels at the frame boundaries,
+modifying its output frame size.
+
+Drivers must not return an error solely because the requested format
+doesn't match the device capabilities. They must instead modify the
+format to match what the hardware can provide. The modified format
+should be as close as possible to the original request.
+
+
+.. _v4l2-subdev-format:
+
+.. flat-table:: struct v4l2_subdev_format
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+
+    -  .. row 1
+
+       -  __u32
+
+       -  ``pad``
+
+       -  Pad number as reported by the media controller API.
+
+    -  .. row 2
+
+       -  __u32
+
+       -  ``which``
+
+       -  Format to modified, from enum
+	  :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
+
+    -  .. row 3
+
+       -  struct :ref:`v4l2_mbus_framefmt <v4l2-mbus-framefmt>`
+
+       -  ``format``
+
+       -  Definition of an image format, see :ref:`v4l2-mbus-framefmt` for
+	  details.
+
+    -  .. row 4
+
+       -  __u32
+
+       -  ``reserved``\ [8]
+
+       -  Reserved for future extensions. Applications and drivers must set
+	  the array to zero.
+
+
+
+.. _v4l2-subdev-format-whence:
+
+.. flat-table:: enum v4l2_subdev_format_whence
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+
+    -  .. row 1
+
+       -  V4L2_SUBDEV_FORMAT_TRY
+
+       -  0
+
+       -  Try formats, used for querying device capabilities.
+
+    -  .. row 2
+
+       -  V4L2_SUBDEV_FORMAT_ACTIVE
+
+       -  1
+
+       -  Active formats, applied to the hardware.
+
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.
+
+EBUSY
+    The format can't be changed because the pad is currently busy. This
+    can be caused, for instance, by an active video stream on the pad.
+    The ioctl must not be retried without performing another action to
+    fix the problem first. Only returned by ``VIDIOC_SUBDEV_S_FMT``
+
+EINVAL
+    The struct :ref:`v4l2_subdev_format <v4l2-subdev-format>`
+    ``pad`` references a non-existing pad, or the ``which`` field
+    references a non-existing format.
+
+
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.