From d0b2f91bede3bd5e3d24dd6803e56eee959c1797 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Thu, 20 Oct 2016 00:10:27 -0300
Subject: Linux-libre 4.8.2-gnu

---
 Documentation/media/uapi/dvb/frontend_f_open.rst | 102 +++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 Documentation/media/uapi/dvb/frontend_f_open.rst

(limited to 'Documentation/media/uapi/dvb/frontend_f_open.rst')

diff --git a/Documentation/media/uapi/dvb/frontend_f_open.rst b/Documentation/media/uapi/dvb/frontend_f_open.rst
new file mode 100644
index 000000000..e0c55345f
--- /dev/null
+++ b/Documentation/media/uapi/dvb/frontend_f_open.rst
@@ -0,0 +1,102 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _frontend_f_open:
+
+*******************
+DVB frontend open()
+*******************
+
+Name
+====
+
+fe-open - Open a frontend device
+
+
+Synopsis
+========
+
+.. code-block:: c
+
+    #include <fcntl.h>
+
+
+.. cpp:function:: int open( const char *device_name, int flags )
+
+
+Arguments
+=========
+
+``device_name``
+    Device to be opened.
+
+``flags``
+    Open flags. Access can either be ``O_RDWR`` or ``O_RDONLY``.
+
+    Multiple opens are allowed with ``O_RDONLY``. In this mode, only
+    query and read ioctls are allowed.
+
+    Only one open is allowed in ``O_RDWR``. In this mode, all ioctls are
+    allowed.
+
+    When the ``O_NONBLOCK`` flag is given, the system calls may return
+    ``EAGAIN`` error code when no data is available or when the device
+    driver is temporarily busy.
+
+    Other flags have no effect.
+
+
+Description
+===========
+
+This system call opens a named frontend device
+(``/dev/dvb/adapter?/frontend?``) for subsequent use. Usually the first
+thing to do after a successful open is to find out the frontend type
+with :ref:`FE_GET_INFO`.
+
+The device can be opened in read-only mode, which only allows monitoring
+of device status and statistics, or read/write mode, which allows any
+kind of use (e.g. performing tuning operations.)
+
+In a system with multiple front-ends, it is usually the case that
+multiple devices cannot be open in read/write mode simultaneously. As
+long as a front-end device is opened in read/write mode, other open()
+calls in read/write mode will either fail or block, depending on whether
+non-blocking or blocking mode was specified. A front-end device opened
+in blocking mode can later be put into non-blocking mode (and vice
+versa) using the F_SETFL command of the fcntl system call. This is a
+standard system call, documented in the Linux manual page for fcntl.
+When an open() call has succeeded, the device will be ready for use in
+the specified mode. This implies that the corresponding hardware is
+powered up, and that other front-ends may have been powered down to make
+that possible.
+
+
+Return Value
+============
+
+On success :ref:`open() <frontend_f_open>` returns the new file descriptor.
+On error, -1 is returned, and the ``errno`` variable is set appropriately.
+
+Possible error codes are:
+
+EACCES
+    The caller has no permission to access the device.
+
+EBUSY
+    The the device driver is already in use.
+
+ENXIO
+    No device corresponding to this device special file exists.
+
+ENOMEM
+    Not enough kernel memory was available to complete the request.
+
+EMFILE
+    The process already has the maximum number of files open.
+
+ENFILE
+    The limit on the total number of files open on the system has been
+    reached.
+
+ENODEV
+    The device got removed.
-- 
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