[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 <[e-mail]>
Signed-off-by: Laurent Pinchart <[e-mail]>
Acked-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/DocBook/media-entities.tmpl

···
 <!ENTITY VIDIOC-S-TUNER "<link linkend='vidioc-g-tuner'><constant>VIDIOC_S_TUNER</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-ENUM-FRAME-SIZE "<link linkend='vidioc-subdev-enum-frame-size'><constant>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-ENUM-MBUS-CODE "<link linkend='vidioc-subdev-enum-mbus-code'><constant>VIDIOC_SUBDEV_ENUM_MBUS_CODE</constant></link>">
+<!ENTITY VIDIOC-SUBDEV-G-CROP "<link linkend='vidioc-subdev-g-crop'><constant>VIDIOC_SUBDEV_G_CROP</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-G-FMT "<link linkend='vidioc-subdev-g-fmt'><constant>VIDIOC_SUBDEV_G_FMT</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-G-FRAME-INTERVAL "<link linkend='vidioc-subdev-g-frame-interval'><constant>VIDIOC_SUBDEV_G_FRAME_INTERVAL</constant></link>">
+<!ENTITY VIDIOC-SUBDEV-S-CROP "<link linkend='vidioc-subdev-g-crop'><constant>VIDIOC_SUBDEV_S_CROP</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-S-FMT "<link linkend='vidioc-subdev-g-fmt'><constant>VIDIOC_SUBDEV_S_FMT</constant></link>">
 <!ENTITY VIDIOC-SUBDEV-S-FRAME-INTERVAL "<link linkend='vidioc-subdev-g-frame-interval'><constant>VIDIOC_SUBDEV_S_FRAME_INTERVAL</constant></link>">
 <!ENTITY VIDIOC-TRY-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_TRY_ENCODER_CMD</constant></link>">
···
 <!ENTITY v4l2-subdev-frame-interval "struct&nbsp;<link linkend='v4l2-subdev-frame-interval'>v4l2_subdev_frame_interval</link>">
 <!ENTITY v4l2-subdev-frame-interval-enum "struct&nbsp;<link linkend='v4l2-subdev-frame-interval-enum'>v4l2_subdev_frame_interval_enum</link>">
 <!ENTITY v4l2-subdev-frame-size-enum "struct&nbsp;<link linkend='v4l2-subdev-frame-size-enum'>v4l2_subdev_frame_size_enum</link>">
+<!ENTITY v4l2-subdev-crop "struct&nbsp;<link linkend='v4l2-subdev-crop'>v4l2_subdev_crop</link>">
 <!ENTITY v4l2-subdev-format "struct&nbsp;<link linkend='v4l2-subdev-format'>v4l2_subdev_format</link>">
 <!ENTITY v4l2-subdev-mbus-code-enum "struct&nbsp;<link linkend='v4l2-subdev-mbus-code-enum'>v4l2_subdev_mbus_code_enum</link>">
 <!ENTITY v4l2-standard "struct&nbsp;<link linkend='v4l2-standard'>v4l2_standard</link>">
···
 <!ENTITY sub-subdev-enum-frame-size SYSTEM "v4l/vidioc-subdev-enum-frame-size.xml">
 <!ENTITY sub-subdev-enum-mbus-code SYSTEM "v4l/vidioc-subdev-enum-mbus-code.xml">
 <!ENTITY sub-subdev-formats SYSTEM "v4l/subdev-formats.xml">
+<!ENTITY sub-subdev-g-crop SYSTEM "v4l/vidioc-subdev-g-crop.xml">
 <!ENTITY sub-subdev-g-fmt SYSTEM "v4l/vidioc-subdev-g-fmt.xml">
 <!ENTITY sub-subdev-g-frame-interval SYSTEM "v4l/vidioc-subdev-g-frame-interval.xml">
 <!ENTITY sub-capture-c SYSTEM "v4l/capture.c.xml">

Documentation/DocBook/v4l/dev-subdev.xml

···
       </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;

Documentation/DocBook/v4l/v4l2.xml

···
     &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;

Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml

···
+<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>

drivers/media/video/v4l2-subdev.c

···
 		return v4l2_subdev_call(sd, pad, set_fmt, subdev_fh, format);
 	}
 
+	case VIDIOC_SUBDEV_G_CROP: {
+		struct v4l2_subdev_crop *crop = arg;
+
+		if (crop->which != V4L2_SUBDEV_FORMAT_TRY &&
+		    crop->which != V4L2_SUBDEV_FORMAT_ACTIVE)
+			return -EINVAL;
+
+		if (crop->pad >= sd->entity.num_pads)
+			return -EINVAL;
+
+		return v4l2_subdev_call(sd, pad, get_crop, subdev_fh, crop);
+	}
+
+	case VIDIOC_SUBDEV_S_CROP: {
+		struct v4l2_subdev_crop *crop = arg;
+
+		if (crop->which != V4L2_SUBDEV_FORMAT_TRY &&
+		    crop->which != V4L2_SUBDEV_FORMAT_ACTIVE)
+			return -EINVAL;
+
+		if (crop->pad >= sd->entity.num_pads)
+			return -EINVAL;
+
+		return v4l2_subdev_call(sd, pad, set_crop, subdev_fh, crop);
+	}
+
 	case VIDIOC_SUBDEV_ENUM_MBUS_CODE: {
 		struct v4l2_subdev_mbus_code_enum *code = arg;
 

include/linux/v4l2-subdev.h

···
 };
 
 /**
+ * struct v4l2_subdev_crop - Pad-level crop settings
+ * @which: format type (from enum v4l2_subdev_format_whence)
+ * @pad: pad number, as reported by the media API
+ * @rect: pad crop rectangle boundaries
+ */
+struct v4l2_subdev_crop {
+	__u32 which;
+	__u32 pad;
+	struct v4l2_rect rect;
+	__u32 reserved[8];
+};
+
+/**
  * struct v4l2_subdev_mbus_code_enum - Media bus format enumeration
  * @pad: pad number, as reported by the media API
  * @index: format index during enumeration
···
 			_IOWR('V', 74, struct v4l2_subdev_frame_size_enum)
 #define VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL \
 			_IOWR('V', 75, struct v4l2_subdev_frame_interval_enum)
+#define VIDIOC_SUBDEV_G_CROP	_IOWR('V', 59, struct v4l2_subdev_crop)
+#define VIDIOC_SUBDEV_S_CROP	_IOWR('V', 60, struct v4l2_subdev_crop)
 
 #endif

include/media/v4l2-subdev.h

···
 		       struct v4l2_subdev_format *format);
 	int (*set_fmt)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
 		       struct v4l2_subdev_format *format);
+	int (*set_crop)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
+		       struct v4l2_subdev_crop *crop);
+	int (*get_crop)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
+		       struct v4l2_subdev_crop *crop);
 };
 
 struct v4l2_subdev_ops {