Hi Sylwester,
On Sunday 13 February 2011 22:59:44 Sylwester Nawrocki wrote:
On 2011-01-27 13:30, Laurent Pinchart wrote:
Create the following two ioctls and implement them at the media device level to enumerate entities, pads and links.
- MEDIA_IOC_ENUM_ENTITIES: Enumerate entities and their properties
- MEDIA_IOC_ENUM_LINKS: Enumerate all pads and links for a given entity
Entity IDs can be non-contiguous. Userspace applications should enumerate entities using the MEDIA_ENT_ID_FLAG_NEXT flag. When the flag is set in the entity ID, the MEDIA_IOC_ENUM_ENTITIES will return the next entity with an ID bigger than the requested one.
Only forward links that originate at one of the entity's source pads are returned during the enumeration process.
Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Sakari Ailus sakari.ailus@maxwell.research.nokia.com
Documentation/DocBook/media-entities.tmpl | 8 + Documentation/DocBook/v4l/media-controller.xml | 2 + .../DocBook/v4l/media-ioc-device-info.xml | 3 +- .../DocBook/v4l/media-ioc-enum-entities.xml | 308 ++++++++++++++++++++ Documentation/DocBook/v4l/media-ioc-enum-links.xml | 202 +++++++++++++ drivers/media/media-device.c | 123 ++++++++ include/linux/media.h | 85 ++++++ include/media/media-entity.h | 24 +-- 8 files changed, 731 insertions(+), 24 deletions(-) create mode 100644 Documentation/DocBook/v4l/media-ioc-enum-entities.xml create mode 100644 Documentation/DocBook/v4l/media-ioc-enum-links.xml
...
diff --git a/Documentation/DocBook/v4l/media-ioc-enum-links.xml b/Documentation/DocBook/v4l/media-ioc-enum-links.xml new file mode 100644 index 0000000..daf0360 --- /dev/null +++ b/Documentation/DocBook/v4l/media-ioc-enum-links.xml @@ -0,0 +1,202 @@ +<refentry id="media-ioc-enum-links">
<refmeta>
- <refentrytitle>ioctl MEDIA_IOC_ENUM_LINKS</refentrytitle>
- &manvol;
</refmeta>
<refnamediv>
- <refname>MEDIA_IOC_ENUM_LINKS</refname>
- <refpurpose>Enumerate all pads and links for a given
entity</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_links_enum
*<parameter>argp</parameter></paramdef> + </funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>- <term><parameter>fd</parameter></term>
<listitem>
<para>File descriptor returned by<linklinkend='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 enumerate pads and/or links for a given entity,
applications set + the entity field of a &media-links-enum; structure and initialize the + &media-pad-desc; and &media-link-desc; structure arrays pointed by the + <structfield>pads</structfield> and <structfield>links</structfield> fields. + They then call the MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this + structure.</para>
- <para>If the <structfield>pads</structfield> field is not NULL, the
driver + fills the <structfield>pads</structfield> array with information about the + entity's pads. The array must have enough room to store all the entity's + pads. The number of pads can be retrieved with the &MEDIA-IOC-ENUM-ENTITIES; + ioctl.</para>
- <para>If the <structfield>links</structfield> field is not NULL, the
driver + fills the <structfield>links</structfield> array with information about the + entity's outbound links. The array must have enough room to store all the + entity's outbound links. The number of outbound links can be retrieved with + the &MEDIA-IOC-ENUM-ENTITIES; ioctl.</para>
- <para>Only forward links that originate at one of the entity's
source pads + are returned during the enumeration process.</para>
<table pgwide="1" frame="none" id="media-links-enum">
<title>struct <structname>media_links_enum</structname></title><tgroup cols="3">&cs-str;<tbody valign="top">
<row><entry>__u32</entry><entry><structfield>entity</structfield></entry><entry>Entity id, set by the application.</entry></row><row><entry>struct &media-pad-desc;</entry><entry>*<structfield>pads</structfield></entry><entry>Pointer to a pads array allocated by the application.Ignored + if NULL.</entry>
</row><row><entry>struct &media-link-desc;</entry><entry>*<structfield>links</structfield></entry><entry>Pointer to a links array allocated by the application.Ignored + if NULL.</entry>
</row></tbody>
</tgroup></table>
<table pgwide="1" frame="none" id="media-pad-desc">
<title>struct <structname>media_pad_desc</structname></title><tgroup cols="3">&cs-str;<tbody valign="top">
<row><entry>__u32</entry><entry><structfield>entity</structfield></entry><entry>ID of the entity this pad belongs to.</entry></row><row><entry>__u16</entry><entry><structfield>index</structfield></entry><entry>0-based pad index.</entry></row><row><entry>__u32</entry><entry><structfield>flags</structfield></entry><entry>Pad flags, see <xref linkend="media-pad-flag" /> for moredetails.</entry> + </row>
</tbody>
</tgroup></table>
<table frame="none" pgwide="1" id="media-pad-flag">
<title>Media pad flags</title><tgroup cols="2"><colspec colname="c1"/><colspec colname="c2"/><tbody valign="top">
<row><entry><constant>MEDIA_PAD_FL_INPUT</constant></entry><entry>Input pad, relative to the entity. Input pads sink data andare targets of links.</entry></row><row><entry><constant>MEDIA_PAD_FL_OUTPUT</constant></entry><entry>Output pad, relative to the entity. Output pads source dataand are origins of links.</entry></row></tbody>
</tgroup></table>
<table pgwide="1" frame="none" id="media-link-desc">
<title>struct <structname>media_links_enum</structname></title>..the above line should perhaps be:
<title>struct <structname>media_links_desc</structname></title>as "struct media_links_desc" is described above.
Thanks for catching this. I'll fix it.
BTW, I was wondering how one makes use of the pads associated with a media entity of type other than MEDIA_ENT_T_V4L2_SUBDEV*, e.g. V4L2 device - MEDIA_ENT_T_DEVNODE_V4L.
I guess new standard ioctls should be added for per pads operations at V4L2 device, similarly is it is done with v4l2-subdevs. Is this right?
I don't think we need now ioctls there. As DEVNODE_V4L entities are just an interface between the driver and userspace, applications should use V4L2 ioctls on the video device node.
For non-V4L entities other ioctls will obviously be needed, but they will be defined by other subsystems such as ALSA (provided the entities have a device node).