Resguardo inicial

linux-7.2.3/Documentation/userspace-api/media/v4l/vidioc-g-input.rst

@@ -0,0 +1,63 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_G_INPUT:
+
+************************************
+ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
+************************************
+
+Name
+====
+
+VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_G_INPUT
+
+``int ioctl(int fd, VIDIOC_G_INPUT, int *argp)``
+
+.. c:macro:: VIDIOC_S_INPUT
+
+``int ioctl(int fd, VIDIOC_S_INPUT, int *argp)``
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :c:func:`open()`.
+
+``argp``
+    Pointer an integer with input index.
+
+Description
+===========
+
+To query the current video input applications call the
+:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
+stores the number of the input, as in the struct
+:c:type:`v4l2_input` ``index`` field. This ioctl will fail
+only when there are no video inputs, returning ``EINVAL``.
+
+To select a video input applications store the number of the desired
+input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
+to this integer. Side effects are possible. For example inputs may
+support different video standards, so the driver may implicitly switch
+the current standard. Because of these possible side effects
+applications must select an input before querying or negotiating any
+other parameters.
+
+Information about video inputs is available using the
+:ref:`VIDIOC_ENUMINPUT` 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 input is out of bounds.