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diff --git a/Documentation/DocBook/media/v4l/func-mmap.xml b/Documentation/DocBook/media/v4l/func-mmap.xml deleted file mode 100644 index f31ad71bf301..000000000000 --- a/Documentation/DocBook/media/v4l/func-mmap.xml +++ /dev/null @@ -1,183 +0,0 @@ -<refentry id="func-mmap"> - <refmeta> - <refentrytitle>V4L2 mmap()</refentrytitle> - &manvol; - </refmeta> - - <refnamediv> - <refname>v4l2-mmap</refname> - <refpurpose>Map device memory into application address space</refpurpose> - </refnamediv> - - <refsynopsisdiv> - <funcsynopsis> - <funcsynopsisinfo> -#include <unistd.h> -#include <sys/mman.h></funcsynopsisinfo> - <funcprototype> - <funcdef>void *<function>mmap</function></funcdef> - <paramdef>void *<parameter>start</parameter></paramdef> - <paramdef>size_t <parameter>length</parameter></paramdef> - <paramdef>int <parameter>prot</parameter></paramdef> - <paramdef>int <parameter>flags</parameter></paramdef> - <paramdef>int <parameter>fd</parameter></paramdef> - <paramdef>off_t <parameter>offset</parameter></paramdef> - </funcprototype> - </funcsynopsis> - </refsynopsisdiv> - - <refsect1> - <title>Arguments</title> - <variablelist> - <varlistentry> - <term><parameter>start</parameter></term> - <listitem> - <para>Map the buffer to this address in the -application's address space. When the <constant>MAP_FIXED</constant> -flag is specified, <parameter>start</parameter> must be a multiple of the -pagesize and mmap will fail when the specified address -cannot be used. Use of this option is discouraged; applications should -just specify a <constant>NULL</constant> pointer here.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>length</parameter></term> - <listitem> - <para>Length of the memory area to map. This must be the -same value as returned by the driver in the &v4l2-buffer; -<structfield>length</structfield> field for the -single-planar API, and the same value as returned by the driver -in the &v4l2-plane; <structfield>length</structfield> field for the -multi-planar API.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>prot</parameter></term> - <listitem> - <para>The <parameter>prot</parameter> argument describes the -desired memory protection. Regardless of the device type and the -direction of data exchange it should be set to -<constant>PROT_READ</constant> | <constant>PROT_WRITE</constant>, -permitting read and write access to image buffers. Drivers should -support at least this combination of flags. Note the Linux -<filename>video-buf</filename> kernel module, which is used by the -bttv, saa7134, saa7146, cx88 and vivi driver supports only -<constant>PROT_READ</constant> | <constant>PROT_WRITE</constant>. When -the driver does not support the desired protection the -<function>mmap()</function> function fails.</para> - <para>Note device memory accesses (⪚ the memory on a -graphics card with video capturing hardware) may incur a performance -penalty compared to main memory accesses, or reads may be -significantly slower than writes or vice versa. Other I/O methods may -be more efficient in this case.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>flags</parameter></term> - <listitem> - <para>The <parameter>flags</parameter> parameter -specifies the type of the mapped object, mapping options and whether -modifications made to the mapped copy of the page are private to the -process or are to be shared with other references.</para> - <para><constant>MAP_FIXED</constant> requests that the -driver selects no other address than the one specified. If the -specified address cannot be used, <function>mmap()</function> will fail. If -<constant>MAP_FIXED</constant> is specified, -<parameter>start</parameter> must be a multiple of the pagesize. Use -of this option is discouraged.</para> - <para>One of the <constant>MAP_SHARED</constant> or -<constant>MAP_PRIVATE</constant> flags must be set. -<constant>MAP_SHARED</constant> allows applications to share the -mapped memory with other (⪚ child-) processes. Note the Linux -<filename>video-buf</filename> module which is used by the bttv, -saa7134, saa7146, cx88 and vivi driver supports only -<constant>MAP_SHARED</constant>. <constant>MAP_PRIVATE</constant> -requests copy-on-write semantics. V4L2 applications should not set the -<constant>MAP_PRIVATE</constant>, <constant>MAP_DENYWRITE</constant>, -<constant>MAP_EXECUTABLE</constant> or <constant>MAP_ANON</constant> -flag.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>fd</parameter></term> - <listitem> - <para>&fd;</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>offset</parameter></term> - <listitem> - <para>Offset of the buffer in device memory. This must be the -same value as returned by the driver in the &v4l2-buffer; -<structfield>m</structfield> union <structfield>offset</structfield> field for -the single-planar API, and the same value as returned by the driver -in the &v4l2-plane; <structfield>m</structfield> union -<structfield>mem_offset</structfield> field for the multi-planar API.</para> - </listitem> - </varlistentry> - </variablelist> - </refsect1> - - <refsect1> - <title>Description</title> - - <para>The <function>mmap()</function> function asks to map -<parameter>length</parameter> bytes starting at -<parameter>offset</parameter> in the memory of the device specified by -<parameter>fd</parameter> into the application address space, -preferably at address <parameter>start</parameter>. This latter -address is a hint only, and is usually specified as 0.</para> - - <para>Suitable length and offset parameters are queried with the -&VIDIOC-QUERYBUF; ioctl. Buffers must be allocated with the -&VIDIOC-REQBUFS; ioctl before they can be queried.</para> - - <para>To unmap buffers the &func-munmap; function is used.</para> - </refsect1> - - <refsect1> - <title>Return Value</title> - - <para>On success <function>mmap()</function> returns a pointer to -the mapped buffer. On error <constant>MAP_FAILED</constant> (-1) is -returned, and the <varname>errno</varname> variable is set -appropriately. Possible error codes are:</para> - - <variablelist> - <varlistentry> - <term><errorcode>EBADF</errorcode></term> - <listitem> - <para><parameter>fd</parameter> is not a valid file -descriptor.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><errorcode>EACCES</errorcode></term> - <listitem> - <para><parameter>fd</parameter> is -not open for reading and writing.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><errorcode>EINVAL</errorcode></term> - <listitem> - <para>The <parameter>start</parameter> or -<parameter>length</parameter> or <parameter>offset</parameter> are not -suitable. (E. g. they are too large, or not aligned on a -<constant>PAGESIZE</constant> boundary.)</para> - <para>The <parameter>flags</parameter> or -<parameter>prot</parameter> value is not supported.</para> - <para>No buffers have been allocated with the -&VIDIOC-REQBUFS; ioctl.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><errorcode>ENOMEM</errorcode></term> - <listitem> - <para>Not enough physical or virtual memory was available to -complete the request.</para> - </listitem> - </varlistentry> - </variablelist> - </refsect1> -</refentry> |