[media] v4l: v4l2_subdev userspace crop API
This patch adds the VIDIOC_SUBDEV_S_CROP and G_CROP ioctls to the
userland API. CROPCAP is not implemented because it's redundant.
Signed-off-by: Antti Koskipaa <akoskipa@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/v4l/dev-subdev.xml b/Documentation/DocBook/v4l/dev-subdev.xml
index fc62e65..e9eb8af 100644
--- a/Documentation/DocBook/v4l/dev-subdev.xml
+++ b/Documentation/DocBook/v4l/dev-subdev.xml
@@ -275,6 +275,39 @@
</para>
</section>
+ <section>
+ <title>Cropping and scaling</title>
+
+ <para>Many sub-devices support cropping frames on their input or output
+ pads (or possible even on both). Cropping is used to select the area of
+ interest in an image, typically on a video sensor or video decoder. It can
+ also be used as part of digital zoom implementations to select the area of
+ the image that will be scaled up.</para>
+
+ <para>Crop settings are defined by a crop rectangle and represented in a
+ &v4l2-rect; by the coordinates of the top left corner and the rectangle
+ size. Both the coordinates and sizes are expressed in pixels.</para>
+
+ <para>The crop rectangle is retrieved and set using the
+ &VIDIOC-SUBDEV-G-CROP; and &VIDIOC-SUBDEV-S-CROP; ioctls. Like for pad
+ formats, drivers store try and active crop rectangles. The format
+ negotiation mechanism applies to crop settings as well.</para>
+
+ <para>On input pads, cropping is applied relatively to the current pad
+ format. The pad format represents the image size as received by the
+ sub-device from the previous block in the pipeline, and the crop rectangle
+ represents the sub-image that will be transmitted further inside the
+ sub-device for processing. The crop rectangle be entirely containted
+ inside the input image size.</para>
+
+ <para>Input crop rectangle are reset to their default value when the input
+ image format is modified. Drivers should use the input image size as the
+ crop rectangle default value, but hardware requirements may prevent this.
+ </para>
+
+ <para>Cropping behaviour on output pads is not defined.</para>
+
+ </section>
</section>
&sub-subdev-formats;
diff --git a/Documentation/DocBook/v4l/v4l2.xml b/Documentation/DocBook/v4l/v4l2.xml
index a436716..3a6e3b5 100644
--- a/Documentation/DocBook/v4l/v4l2.xml
+++ b/Documentation/DocBook/v4l/v4l2.xml
@@ -510,6 +510,7 @@
&sub-subdev-enum-frame-interval;
&sub-subdev-enum-frame-size;
&sub-subdev-enum-mbus-code;
+ &sub-subdev-g-crop;
&sub-subdev-g-fmt;
&sub-subdev-g-frame-interval;
&sub-subscribe-event;
diff --git a/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml
new file mode 100644
index 0000000..0619732
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml
@@ -0,0 +1,155 @@
+<refentry id="vidioc-subdev-g-crop">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_SUBDEV_G_CROP</refname>
+ <refname>VIDIOC_SUBDEV_S_CROP</refname>
+ <refpurpose>Get or set the crop rectangle on a subdev pad</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 v4l2_subdev_crop *<parameter>argp</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>const struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Arguments</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><parameter>fd</parameter></term>
+ <listitem>
+ <para>&fd;</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>request</parameter></term>
+ <listitem>
+ <para>VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <note>
+ <title>Experimental</title>
+ <para>This is an <link linkend="experimental">experimental</link>
+ interface and may change in the future.</para>
+ </note>
+
+ <para>To retrieve the current crop rectangle applications set the
+ <structfield>pad</structfield> field of a &v4l2-subdev-crop; to the
+ desired pad number as reported by the media API and the
+ <structfield>which</structfield> field to
+ <constant>V4L2_SUBDEV_FORMAT_ACTIVE</constant>. They then call the
+ <constant>VIDIOC_SUBDEV_G_CROP</constant> ioctl with a pointer to this
+ structure. The driver fills the members of the <structfield>rect</structfield>
+ field or returns &EINVAL; if the input arguments are invalid, or if cropping
+ is not supported on the given pad.</para>
+
+ <para>To change the current crop rectangle applications set both the
+ <structfield>pad</structfield> and <structfield>which</structfield> fields
+ and all members of the <structfield>rect</structfield> field. They then call
+ the <constant>VIDIOC_SUBDEV_S_CROP</constant> ioctl with a pointer to this
+ structure. The driver verifies the requested crop rectangle, adjusts it
+ based on the hardware capabilities and configures the device. Upon return
+ the &v4l2-subdev-crop; contains the current format as would be returned
+ by a <constant>VIDIOC_SUBDEV_G_CROP</constant> call.</para>
+
+ <para>Applications can query the device capabilities by setting the
+ <structfield>which</structfield> to
+ <constant>V4L2_SUBDEV_FORMAT_TRY</constant>. When set, 'try' crop
+ rectangles are not applied to the device by the driver, but are mangled
+ exactly as active crop rectangles and stored in the sub-device file handle.
+ Two applications querying the same sub-device would thus not interact with
+ each other.</para>
+
+ <para>Drivers must not return an error solely because the requested crop
+ rectangle doesn't match the device capabilities. They must instead modify
+ the rectangle to match what the hardware can provide. The modified format
+ should be as close as possible to the original request.</para>
+
+ <table pgwide="1" frame="none" id="v4l2-subdev-crop">
+ <title>struct <structname>v4l2_subdev_crop</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>pad</structfield></entry>
+ <entry>Pad number as reported by the media framework.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>which</structfield></entry>
+ <entry>Crop rectangle to get or set, from
+ &v4l2-subdev-format-whence;.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-rect;</entry>
+ <entry><structfield>rect</structfield></entry>
+ <entry>Crop rectangle boundaries, in pixels.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[8]</entry>
+ <entry>Reserved for future extensions. Applications and drivers must
+ set the array to zero.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EBUSY</errorcode></term>
+ <listitem>
+ <para>The crop rectangle can't be changed because the pad is currently
+ busy. This can be caused, for instance, by an active video stream on
+ the pad. The ioctl must not be retried without performing another
+ action to fix the problem first. Only returned by
+ <constant>VIDIOC_SUBDEV_S_CROP</constant></para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The &v4l2-subdev-crop; <structfield>pad</structfield>
+ references a non-existing pad, the <structfield>which</structfield>
+ field references a non-existing format, or cropping is not supported
+ on the given subdev pad.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>