doc_rst: rename the media Sphinx suff to Documentation/media

[cascardo/linux.git] / Documentation / media / uapi / v4l / vidioc-g-output.rst

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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _VIDIOC_G_OUTPUT:
+
+**************************************
+ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
+**************************************
+
+Name
+====
+
+VIDIOC_G_OUTPUT - VIDIOC_S_OUTPUT - Query or select the current video output
+
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, int *argp )
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+    VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
+
+``argp``
+
+
+Description
+===========
+
+To query the current video output applications call the
+:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver
+stores the number of the output, as in the struct
+:ref:`v4l2_output <v4l2-output>` ``index`` field. This ioctl will
+fail only when there are no video outputs, returning the ``EINVAL`` error
+code.
+
+To select a video output applications store the number of the desired
+output in an integer and call the :ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a
+pointer to this integer. Side effects are possible. For example outputs
+may support different video standards, so the driver may implicitly
+switch the current standard. standard. Because of these possible side
+effects applications must select an output before querying or
+negotiating any other parameters.
+
+Information about video outputs is available using the
+:ref:`VIDIOC_ENUMOUTPUT` ioctl.
+
+
+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.
+
+EINVAL
+    The number of the video output is out of bounds, or there are no
+    video outputs at all.