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author | Anton Vorontsov <avorontsov@ru.mvista.com> | 2009-09-22 19:49:27 -0400 |
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committer | Anton Vorontsov <avorontsov@ru.mvista.com> | 2009-09-22 19:49:27 -0400 |
commit | f056878332a91ed984a116bad4e7d49aefff9e6e (patch) | |
tree | 572f4757c8e7811d45e0be0c2ae529c78fb63441 /Documentation/DocBook/v4l/func-write.xml | |
parent | 3961f7c3cf247eee5df7fabadc7a40f2deeb98f3 (diff) | |
parent | 7fa07729e439a6184bd824746d06a49cca553f15 (diff) |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
drivers/power/wm97xx_battery.c
Diffstat (limited to 'Documentation/DocBook/v4l/func-write.xml')
-rw-r--r-- | Documentation/DocBook/v4l/func-write.xml | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/func-write.xml b/Documentation/DocBook/v4l/func-write.xml new file mode 100644 index 000000000000..2c09c09371c3 --- /dev/null +++ b/Documentation/DocBook/v4l/func-write.xml | |||
@@ -0,0 +1,136 @@ | |||
1 | <refentry id="func-write"> | ||
2 | <refmeta> | ||
3 | <refentrytitle>V4L2 write()</refentrytitle> | ||
4 | &manvol; | ||
5 | </refmeta> | ||
6 | |||
7 | <refnamediv> | ||
8 | <refname>v4l2-write</refname> | ||
9 | <refpurpose>Write to a V4L2 device</refpurpose> | ||
10 | </refnamediv> | ||
11 | |||
12 | <refsynopsisdiv> | ||
13 | <funcsynopsis> | ||
14 | <funcsynopsisinfo>#include <unistd.h></funcsynopsisinfo> | ||
15 | <funcprototype> | ||
16 | <funcdef>ssize_t <function>write</function></funcdef> | ||
17 | <paramdef>int <parameter>fd</parameter></paramdef> | ||
18 | <paramdef>void *<parameter>buf</parameter></paramdef> | ||
19 | <paramdef>size_t <parameter>count</parameter></paramdef> | ||
20 | </funcprototype> | ||
21 | </funcsynopsis> | ||
22 | </refsynopsisdiv> | ||
23 | |||
24 | <refsect1> | ||
25 | <title>Arguments</title> | ||
26 | |||
27 | <variablelist> | ||
28 | <varlistentry> | ||
29 | <term><parameter>fd</parameter></term> | ||
30 | <listitem> | ||
31 | <para>&fd;</para> | ||
32 | </listitem> | ||
33 | </varlistentry> | ||
34 | <varlistentry> | ||
35 | <term><parameter>buf</parameter></term> | ||
36 | <listitem> | ||
37 | <para></para> | ||
38 | </listitem> | ||
39 | </varlistentry> | ||
40 | <varlistentry> | ||
41 | <term><parameter>count</parameter></term> | ||
42 | <listitem> | ||
43 | <para></para> | ||
44 | </listitem> | ||
45 | </varlistentry> | ||
46 | </variablelist> | ||
47 | </refsect1> | ||
48 | |||
49 | <refsect1> | ||
50 | <title>Description</title> | ||
51 | |||
52 | <para><function>write()</function> writes up to | ||
53 | <parameter>count</parameter> bytes to the device referenced by the | ||
54 | file descriptor <parameter>fd</parameter> from the buffer starting at | ||
55 | <parameter>buf</parameter>. When the hardware outputs are not active | ||
56 | yet, this function enables them. When <parameter>count</parameter> is | ||
57 | zero, <function>write()</function> returns | ||
58 | <returnvalue>0</returnvalue> without any other effect.</para> | ||
59 | |||
60 | <para>When the application does not provide more data in time, the | ||
61 | previous video frame, raw VBI image, sliced VPS or WSS data is | ||
62 | displayed again. Sliced Teletext or Closed Caption data is not | ||
63 | repeated, the driver inserts a blank line instead.</para> | ||
64 | </refsect1> | ||
65 | |||
66 | <refsect1> | ||
67 | <title>Return Value</title> | ||
68 | |||
69 | <para>On success, the number of bytes written are returned. Zero | ||
70 | indicates nothing was written. On error, <returnvalue>-1</returnvalue> | ||
71 | is returned, and the <varname>errno</varname> variable is set | ||
72 | appropriately. In this case the next write will start at the beginning | ||
73 | of a new frame. Possible error codes are:</para> | ||
74 | |||
75 | <variablelist> | ||
76 | <varlistentry> | ||
77 | <term><errorcode>EAGAIN</errorcode></term> | ||
78 | <listitem> | ||
79 | <para>Non-blocking I/O has been selected using the <link | ||
80 | linkend="func-open"><constant>O_NONBLOCK</constant></link> flag and no | ||
81 | buffer space was available to write the data immediately.</para> | ||
82 | </listitem> | ||
83 | </varlistentry> | ||
84 | <varlistentry> | ||
85 | <term><errorcode>EBADF</errorcode></term> | ||
86 | <listitem> | ||
87 | <para><parameter>fd</parameter> is not a valid file | ||
88 | descriptor or is not open for writing.</para> | ||
89 | </listitem> | ||
90 | </varlistentry> | ||
91 | <varlistentry> | ||
92 | <term><errorcode>EBUSY</errorcode></term> | ||
93 | <listitem> | ||
94 | <para>The driver does not support multiple write streams and the | ||
95 | device is already in use.</para> | ||
96 | </listitem> | ||
97 | </varlistentry> | ||
98 | <varlistentry> | ||
99 | <term><errorcode>EFAULT</errorcode></term> | ||
100 | <listitem> | ||
101 | <para><parameter>buf</parameter> references an inaccessible | ||
102 | memory area.</para> | ||
103 | </listitem> | ||
104 | </varlistentry> | ||
105 | <varlistentry> | ||
106 | <term><errorcode>EINTR</errorcode></term> | ||
107 | <listitem> | ||
108 | <para>The call was interrupted by a signal before any | ||
109 | data was written.</para> | ||
110 | </listitem> | ||
111 | </varlistentry> | ||
112 | <varlistentry> | ||
113 | <term><errorcode>EIO</errorcode></term> | ||
114 | <listitem> | ||
115 | <para>I/O error. This indicates some hardware problem.</para> | ||
116 | </listitem> | ||
117 | </varlistentry> | ||
118 | <varlistentry> | ||
119 | <term><errorcode>EINVAL</errorcode></term> | ||
120 | <listitem> | ||
121 | <para>The <function>write()</function> function is not | ||
122 | supported by this driver, not on this device, or generally not on this | ||
123 | type of device.</para> | ||
124 | </listitem> | ||
125 | </varlistentry> | ||
126 | </variablelist> | ||
127 | </refsect1> | ||
128 | </refentry> | ||
129 | |||
130 | <!-- | ||
131 | Local Variables: | ||
132 | mode: sgml | ||
133 | sgml-parent-document: "v4l2.sgml" | ||
134 | indent-tabs-mode: nil | ||
135 | End: | ||
136 | --> | ||