Commit f44026db authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab

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: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 226c0eea
......@@ -21,11 +21,15 @@ API.</para>
<title>Opening and Closing Devices</title>
<para>For compatibility reasons the character device file names
recommended for V4L2 video capture, overlay, radio, teletext and raw
recommended for V4L2 video capture, overlay, radio and raw
vbi capture devices did not change from those used by V4L. They are
listed in <xref linkend="devices" /> and below in <xref
linkend="v4l-dev" />.</para>
<para>The teletext devices (minor range 192-223) have been removed in
V4L2 and no longer exist. There is no hardware available anymore for handling
pure teletext. Instead raw or sliced VBI is used.</para>
<para>The V4L <filename>videodev</filename> module automatically
assigns minor numbers to drivers in load order, depending on the
registered device type. We recommend that V4L2 drivers by default
......@@ -65,13 +69,6 @@ not compatible with V4L or V4L2.</para> </footnote>,
<filename>/dev/radio63</filename></para></entry>
<entry>64-127</entry>
</row>
<row>
<entry>Teletext decoder</entry>
<entry><para><filename>/dev/vtx</filename>,
<filename>/dev/vtx0</filename> to
<filename>/dev/vtx31</filename></para></entry>
<entry>192-223</entry>
</row>
<row>
<entry>Raw VBI capture</entry>
<entry><para><filename>/dev/vbi</filename>,
......@@ -2345,6 +2342,17 @@ more information.</para>
</listitem>
</orderedlist>
</section>
<section>
<title>V4L2 in Linux 2.6.37</title>
<orderedlist>
<listitem>
<para>Remove the vtx (videotext/teletext) API. This API was no longer
used and no hardware exists to verify the API. Nor were any userspace applications found
that used it. It was originally scheduled for removal in 2.6.35.
</para>
</listitem>
</orderedlist>
</section>
<section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title>
......
<title>Teletext Interface</title>
<para>This interface aims at devices receiving and demodulating
<para>This interface was aimed at devices receiving and demodulating
Teletext data [<xref linkend="ets300706" />, <xref linkend="itu653" />], evaluating the
Teletext packages and storing formatted pages in cache memory. Such
devices are usually implemented as microcontrollers with serial
interface (I<superscript>2</superscript>C) and can be found on older
interface (I<superscript>2</superscript>C) and could be found on old
TV cards, dedicated Teletext decoding cards and home-brew devices
connected to the PC parallel port.</para>
<para>The Teletext API was designed by Martin Buck. It is defined in
<para>The Teletext API was designed by Martin Buck. It was defined in
the kernel header file <filename>linux/videotext.h</filename>, the
specification is available from <ulink url="ftp://ftp.gwdg.de/pub/linux/misc/videotext/">
ftp://ftp.gwdg.de/pub/linux/misc/videotext/</ulink>. (Videotext is the name of
the German public television Teletext service.) Conventional character
device file names are <filename>/dev/vtx</filename> and
<filename>/dev/vttuner</filename>, with device number 83, 0 and 83, 16
respectively. A similar interface exists for the Philips SAA5249
Teletext decoder [specification?] with character device file names
<filename>/dev/tlkN</filename>, device number 102, N.</para>
the German public television Teletext service.)</para>
<para>Eventually the Teletext API was integrated into the V4L API
with character device file names <filename>/dev/vtx0</filename> to
<filename>/dev/vtx31</filename>, device major number 81, minor numbers
192 to 223. For reference the V4L Teletext API specification is
reproduced here in full: "Teletext interfaces talk the existing VTX
API." Teletext devices with major number 83 and 102 will be removed in
Linux 2.6.</para>
192 to 223.</para>
<para>There are no plans to replace the Teletext API or to integrate
it into V4L2. Please write to the linux-media mailing list: &v4l-ml;
when the need arises.</para>
<para>However, teletext decoders were quickly replaced by more
generic VBI demodulators and those dedicated teletext decoders no longer exist.
For many years the vtx devices were still around, even though nobody used
them. So the decision was made to finally remove support for the Teletext API in
kernel 2.6.37.</para>
<para>Modern devices all use the <link linkend="raw-vbi">raw</link> or
<link linkend="sliced">sliced</link> VBI API.</para>
<!--
Local Variables:
......
......@@ -99,6 +99,7 @@ Remote Controller chapter.</contrib>
<year>2007</year>
<year>2008</year>
<year>2009</year>
<year>2010</year>
<holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin
Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab</holder>
</copyright>
......@@ -110,9 +111,16 @@ Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab</holder>
<!-- Put document revisions here, newest first. -->
<!-- API revisions (changes and additions of defines, enums,
structs, ioctls) must be noted in more detail in the history chapter
(compat.sgml), along with the possible impact on existing drivers and
(compat.xml), along with the possible impact on existing drivers and
applications. -->
<revision>
<revnumber>2.6.37</revnumber>
<date>2010-08-06</date>
<authorinitials>hv</authorinitials>
<revremark>Removed obsolete vtx (videotext) API.</revremark>
</revision>
<revision>
<revnumber>2.6.33</revnumber>
<date>2009-12-03</date>
......
......@@ -498,29 +498,6 @@ When: April 2011
Why: Superseded by xt_CT
Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
---------------------------
What: video4linux /dev/vtx teletext API support
When: 2.6.35
Files: drivers/media/video/saa5246a.c drivers/media/video/saa5249.c
include/linux/videotext.h
Why: The vtx device nodes have been superseded by vbi device nodes
for many years. No applications exist that use the vtx support.
Of the two i2c drivers that actually support this API the saa5249
has been impossible to use for a year now and no known hardware
that supports this device exists. The saa5246a is theoretically
supported by the old mxb boards, but it never actually worked.
In summary: there is no hardware that can use this API and there
are no applications actually implementing this API.
The vtx support still reserves minors 192-223 and we would really
like to reuse those for upcoming new functionality. In the unlikely
event that new hardware appears that wants to use the functionality
provided by the vtx API, then that functionality should be build
around the sliced VBI API instead.
Who: Hans Verkuil <hverkuil@xs4all.nl>
----------------------------
What: IRQF_DISABLED
......
......@@ -278,7 +278,6 @@ Code Seq#(hex) Include File Comments
<mailto:oe@port.de>
'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
0x80 00-1F linux/fb.h
0x81 00-1F linux/videotext.h
0x88 00-3F media/ovcamchip.h
0x89 00-06 arch/x86/include/asm/sockios.h
0x89 0B-DF linux/sockios.h
......
......@@ -19,7 +19,6 @@ function makedev () {
echo "*** new device names ***"
makedev video 0
makedev radio 64
makedev vtx 192
makedev vbi 224
#echo "*** old device names (for compatibility only) ***"
......
......@@ -44,8 +44,8 @@ All drivers have the following structure:
2) A way of initializing and commanding sub-devices (if any).
3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX, /dev/radioX and
/dev/vtxX) and keeping track of device-node specific data.
3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX and /dev/radioX)
and keeping track of device-node specific data.
4) Filehandle-specific structs containing per-filehandle data;
......@@ -488,7 +488,6 @@ types exist:
VFL_TYPE_GRABBER: videoX for video input/output devices
VFL_TYPE_VBI: vbiX for vertical blank data (i.e. closed captions, teletext)
VFL_TYPE_RADIO: radioX for radio tuners
VFL_TYPE_VTX: vtxX for teletext devices (deprecated, don't use)
The last argument gives you a certain amount of control over the device
device node number used (i.e. the X in videoX). Normally you will pass -1
......
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