[media] media: Links setup

Create the following ioctl and implement it at the media device level to
setup links.

- MEDIA_IOC_SETUP_LINK: Modify the properties of a given link

The only property that can currently be modified is the ENABLED link
flag to enable/disable a link. Links marked with the IMMUTABLE link flag
can not be enabled or disabled.

Enabling or disabling a link has effects on entities' use count. Those
changes are automatically propagated through the graph.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Laurent Pinchart 2009-12-09 08:40:03 -03:00 • committed by Mauro Carvalho Chehab
commit 97548ed4c4
9 changed files with 356 additions and 0 deletions

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@ -94,6 +94,7 @@
<!ENTITY MEDIA-IOC-DEVICE-INFO "<link linkend='media-ioc-device-info'><constant>MEDIA_IOC_DEVICE_INFO</constant></link>">
<!ENTITY MEDIA-IOC-ENUM-ENTITIES "<link linkend='media-ioc-enum-entities'><constant>MEDIA_IOC_ENUM_ENTITIES</constant></link>">
<!ENTITY MEDIA-IOC-ENUM-LINKS "<link linkend='media-ioc-enum-links'><constant>MEDIA_IOC_ENUM_LINKS</constant></link>">
<!ENTITY MEDIA-IOC-SETUP-LINK "<link linkend='media-ioc-setup-link'><constant>MEDIA_IOC_SETUP_LINK</constant></link>">
<!-- Types -->
<!ENTITY v4l2-std-id "<link linkend='v4l2-std-id'>v4l2_std_id</link>">
@ -348,6 +349,7 @@
<!ENTITY sub-media-ioc-device-info SYSTEM "v4l/media-ioc-device-info.xml">
<!ENTITY sub-media-ioc-enum-entities SYSTEM "v4l/media-ioc-enum-entities.xml">
<!ENTITY sub-media-ioc-enum-links SYSTEM "v4l/media-ioc-enum-links.xml">
<!ENTITY sub-media-ioc-setup-link SYSTEM "v4l/media-ioc-setup-link.xml">
<!-- Function Reference -->
<!ENTITY close SYSTEM "v4l/func-close.xml">

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@ -85,4 +85,5 @@
&sub-media-ioc-device-info;
&sub-media-ioc-enum-entities;
&sub-media-ioc-enum-links;
&sub-media-ioc-setup-link;
</appendix>

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@ -0,0 +1,90 @@
<refentry id="media-ioc-setup-link">
<refmeta>
<refentrytitle>ioctl MEDIA_IOC_SETUP_LINK</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>MEDIA_IOC_SETUP_LINK</refname>
<refpurpose>Modify the properties of a link</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>struct media_link_desc *<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>File descriptor returned by
<link linkend='media-func-open'><function>open()</function></link>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>MEDIA_IOC_ENUM_LINKS</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>To change link properties applications fill a &media-link-desc; with
link identification information (source and sink pad) and the new requested
link flags. They then call the MEDIA_IOC_SETUP_LINK ioctl with a pointer to
that structure.</para>
<para>The only configurable property is the <constant>ENABLED</constant>
link flag to enable/disable a link. Links marked with the
<constant>IMMUTABLE</constant> link flag can not be enabled or disabled.
</para>
<para>Link configuration has no side effect on other links. If an enabled
link at the sink pad prevents the link from being enabled, the driver
returns with an &EBUSY;.</para>
<para>If the specified link can't be found the driver returns with an
&EINVAL;.</para>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>EBUSY</errorcode></term>
<listitem>
<para>The link properties can't be changed because the link is
currently busy. This can be caused, for instance, by an active media
stream (audio or video) on the link. The ioctl shouldn't be retried if
no other action is performed before to fix the problem.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>The &media-link-desc; references a non-existing link, or the
link is immutable and an attempt to modify its configuration was made.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>