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Message-Id: <201102141311.48969.laurent.pinchart@ideasonboard.com> Date: Mon, 14 Feb 2011 13:11:48 +0100 From: Laurent Pinchart <laurent.pinchart@...asonboard.com> To: Sylwester Nawrocki <snjw23@...il.com> Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, alsa-devel@...a-project.org, clemens@...isch.de, broonie@...nsource.wolfsonmicro.com, sakari.ailus@...well.research.nokia.com Subject: Re: [PATCH v8 07/12] media: Entities, pads and links enumeration 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@...asonboard.com> > > Signed-off-by: Sakari Ailus <sakari.ailus@...well.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 > > + <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 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 more > > details.</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 and > > + are targets of links.</entry> > > + </row> > > + <row> > > + <entry><constant>MEDIA_PAD_FL_OUTPUT</constant></entry> > > + <entry>Output pad, relative to the entity. Output pads source data > > + and 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). -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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