V4L/DVB: Documentation: update now that the vtx/videotext API has been removed
Remove all references to /dev/vtx in the documentation, except for some historical comments in dev-teletext.xml. Documentation/devices.txt is not updated, this will go through Alan Cox who maintains this file. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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Hans Verkuil
Mauro Carvalho Chehab
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226c0eeaea
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f44026dbe4
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@ -21,11 +21,15 @@ API.</para>
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<title>Opening and Closing Devices</title>
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<para>For compatibility reasons the character device file names
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recommended for V4L2 video capture, overlay, radio, teletext and raw
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recommended for V4L2 video capture, overlay, radio and raw
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vbi capture devices did not change from those used by V4L. They are
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listed in <xref linkend="devices" /> and below in <xref
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linkend="v4l-dev" />.</para>
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<para>The teletext devices (minor range 192-223) have been removed in
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V4L2 and no longer exist. There is no hardware available anymore for handling
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pure teletext. Instead raw or sliced VBI is used.</para>
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<para>The V4L <filename>videodev</filename> module automatically
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assigns minor numbers to drivers in load order, depending on the
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registered device type. We recommend that V4L2 drivers by default
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@ -65,13 +69,6 @@ not compatible with V4L or V4L2.</para> </footnote>,
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<filename>/dev/radio63</filename></para></entry>
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<entry>64-127</entry>
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</row>
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<row>
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<entry>Teletext decoder</entry>
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<entry><para><filename>/dev/vtx</filename>,
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<filename>/dev/vtx0</filename> to
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<filename>/dev/vtx31</filename></para></entry>
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<entry>192-223</entry>
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</row>
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<row>
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<entry>Raw VBI capture</entry>
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<entry><para><filename>/dev/vbi</filename>,
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@ -2345,6 +2342,17 @@ more information.</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>V4L2 in Linux 2.6.37</title>
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<orderedlist>
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<listitem>
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<para>Remove the vtx (videotext/teletext) API. This API was no longer
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used and no hardware exists to verify the API. Nor were any userspace applications found
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that used it. It was originally scheduled for removal in 2.6.35.
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</para>
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</listitem>
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</orderedlist>
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</section>
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<section id="other">
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<title>Relation of V4L2 to other Linux multimedia APIs</title>
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@ -1,35 +1,32 @@
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<title>Teletext Interface</title>
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<para>This interface aims at devices receiving and demodulating
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<para>This interface was aimed at devices receiving and demodulating
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Teletext data [<xref linkend="ets300706" />, <xref linkend="itu653" />], evaluating the
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Teletext packages and storing formatted pages in cache memory. Such
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devices are usually implemented as microcontrollers with serial
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interface (I<superscript>2</superscript>C) and can be found on older
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interface (I<superscript>2</superscript>C) and could be found on old
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TV cards, dedicated Teletext decoding cards and home-brew devices
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connected to the PC parallel port.</para>
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<para>The Teletext API was designed by Martin Buck. It is defined in
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<para>The Teletext API was designed by Martin Buck. It was defined in
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the kernel header file <filename>linux/videotext.h</filename>, the
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specification is available from <ulink url="ftp://ftp.gwdg.de/pub/linux/misc/videotext/">
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ftp://ftp.gwdg.de/pub/linux/misc/videotext/</ulink>. (Videotext is the name of
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the German public television Teletext service.) Conventional character
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device file names are <filename>/dev/vtx</filename> and
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<filename>/dev/vttuner</filename>, with device number 83, 0 and 83, 16
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respectively. A similar interface exists for the Philips SAA5249
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Teletext decoder [specification?] with character device file names
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<filename>/dev/tlkN</filename>, device number 102, N.</para>
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the German public television Teletext service.)</para>
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<para>Eventually the Teletext API was integrated into the V4L API
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with character device file names <filename>/dev/vtx0</filename> to
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<filename>/dev/vtx31</filename>, device major number 81, minor numbers
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192 to 223. For reference the V4L Teletext API specification is
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reproduced here in full: "Teletext interfaces talk the existing VTX
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API." Teletext devices with major number 83 and 102 will be removed in
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Linux 2.6.</para>
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192 to 223.</para>
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<para>There are no plans to replace the Teletext API or to integrate
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it into V4L2. Please write to the linux-media mailing list: &v4l-ml;
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when the need arises.</para>
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<para>However, teletext decoders were quickly replaced by more
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generic VBI demodulators and those dedicated teletext decoders no longer exist.
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For many years the vtx devices were still around, even though nobody used
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them. So the decision was made to finally remove support for the Teletext API in
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kernel 2.6.37.</para>
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<para>Modern devices all use the <link linkend="raw-vbi">raw</link> or
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<link linkend="sliced">sliced</link> VBI API.</para>
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<!--
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Local Variables:
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@ -99,6 +99,7 @@ Remote Controller chapter.</contrib>
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<year>2007</year>
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<year>2008</year>
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<year>2009</year>
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<year>2010</year>
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<holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin
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Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab</holder>
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</copyright>
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@ -110,9 +111,16 @@ Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab</holder>
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<!-- Put document revisions here, newest first. -->
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<!-- API revisions (changes and additions of defines, enums,
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structs, ioctls) must be noted in more detail in the history chapter
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(compat.sgml), along with the possible impact on existing drivers and
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(compat.xml), along with the possible impact on existing drivers and
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applications. -->
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<revision>
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<revnumber>2.6.37</revnumber>
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<date>2010-08-06</date>
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<authorinitials>hv</authorinitials>
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<revremark>Removed obsolete vtx (videotext) API.</revremark>
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</revision>
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<revision>
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<revnumber>2.6.33</revnumber>
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<date>2009-12-03</date>
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@ -498,29 +498,6 @@ When: April 2011
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Why: Superseded by xt_CT
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Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
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---------------------------
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What: video4linux /dev/vtx teletext API support
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When: 2.6.35
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Files: drivers/media/video/saa5246a.c drivers/media/video/saa5249.c
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include/linux/videotext.h
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Why: The vtx device nodes have been superseded by vbi device nodes
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for many years. No applications exist that use the vtx support.
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Of the two i2c drivers that actually support this API the saa5249
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has been impossible to use for a year now and no known hardware
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that supports this device exists. The saa5246a is theoretically
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supported by the old mxb boards, but it never actually worked.
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In summary: there is no hardware that can use this API and there
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are no applications actually implementing this API.
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The vtx support still reserves minors 192-223 and we would really
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like to reuse those for upcoming new functionality. In the unlikely
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event that new hardware appears that wants to use the functionality
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provided by the vtx API, then that functionality should be build
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around the sliced VBI API instead.
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Who: Hans Verkuil <hverkuil@xs4all.nl>
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----------------------------
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What: IRQF_DISABLED
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@ -278,7 +278,6 @@ Code Seq#(hex) Include File Comments
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<mailto:oe@port.de>
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'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
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0x80 00-1F linux/fb.h
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0x81 00-1F linux/videotext.h
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0x88 00-3F media/ovcamchip.h
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0x89 00-06 arch/x86/include/asm/sockios.h
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0x89 0B-DF linux/sockios.h
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@ -19,7 +19,6 @@ function makedev () {
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echo "*** new device names ***"
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makedev video 0
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makedev radio 64
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makedev vtx 192
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makedev vbi 224
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#echo "*** old device names (for compatibility only) ***"
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@ -44,8 +44,8 @@ All drivers have the following structure:
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2) A way of initializing and commanding sub-devices (if any).
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3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX, /dev/radioX and
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/dev/vtxX) and keeping track of device-node specific data.
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3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX and /dev/radioX)
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and keeping track of device-node specific data.
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4) Filehandle-specific structs containing per-filehandle data;
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@ -488,7 +488,6 @@ types exist:
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VFL_TYPE_GRABBER: videoX for video input/output devices
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VFL_TYPE_VBI: vbiX for vertical blank data (i.e. closed captions, teletext)
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VFL_TYPE_RADIO: radioX for radio tuners
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VFL_TYPE_VTX: vtxX for teletext devices (deprecated, don't use)
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The last argument gives you a certain amount of control over the device
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device node number used (i.e. the X in videoX). Normally you will pass -1
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