1 files changed, 73 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/mediactl/request-func-poll.rst b/Documentation/userspace-api/media/mediactl/request-func-poll.rst
new file mode 100644
index 000000000..ce0043dbe
--- /dev/null
+++ b/Documentation/userspace-api/media/mediactl/request-func-poll.rst
@@ -0,0 +1,73 @@
+.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later
+.. c:namespace:: MC
+
+.. _request-func-poll:
+
+**************
+request poll()
+**************
+
+Name
+====
+
+request-poll - Wait for some event on a file descriptor
+
+Synopsis
+========
+
+.. code-block:: c
+
+    #include <sys/poll.h>
+
+.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )
+
+Arguments
+=========
+
+``ufds``
+   List of file descriptor events to be watched
+
+``nfds``
+   Number of file descriptor events at the \*ufds array
+
+``timeout``
+   Timeout to wait for events
+
+Description
+===========
+
+With the :c:func:`poll()` function applications can wait
+for a request to complete.
+
+On success :c:func:`poll()` returns the number of file
+descriptors that have been selected (that is, file descriptors for which the
+``revents`` field of the respective struct :c:type:`pollfd`
+is non-zero). Request file descriptor set the ``POLLPRI`` flag in ``revents``
+when the request was completed.  When the function times out it returns
+a value of zero, on failure it returns -1 and the ``errno`` variable is
+set appropriately.
+
+Attempting to poll for a request that is not yet queued will
+set the ``POLLERR`` flag in ``revents``.
+
+Return Value
+============
+
+On success, :c:func:`poll()` returns the number of
+structures which have non-zero ``revents`` fields, or zero if the call
+timed out. On error -1 is returned, and the ``errno`` variable is set
+appropriately:
+
+``EBADF``
+    One or more of the ``ufds`` members specify an invalid file
+    descriptor.
+
+``EFAULT``
+    ``ufds`` references an inaccessible memory area.
+
+``EINTR``
+    The call was interrupted by a signal.
+
+``EINVAL``
+    The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use
+    ``getrlimit()`` to obtain this value.