linux-kernel - [PATCHv2 1/3] media: v4l UAPI docs: document ROI selection targets

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Date:   Mon,  8 Feb 2021 14:17:47 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Tomasz Figa <tomasz.figa@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        sergey.senozhatsky@...il.com,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCHv2 1/3] media: v4l UAPI docs: document ROI selection targets

From: Sergey Senozhatsky <senozhatsky@...omium.org>

Document new v4l2-selection target which will be used for the
Region of Interest v4l2 control.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 .../media/v4l/selection-api-configuration.rst | 23 +++++++++++++++++++
 .../media/v4l/v4l2-selection-targets.rst      | 21 +++++++++++++++++
 include/uapi/linux/v4l2-common.h              |  8 +++++++
 3 files changed, 52 insertions(+)

diff --git a/Documentation/userspace-api/media/v4l/selection-api-configuration.rst b/Documentation/userspace-api/media/v4l/selection-api-configuration.rst
index fee49bf1a1c0..9f69d71803f6 100644
--- a/Documentation/userspace-api/media/v4l/selection-api-configuration.rst
+++ b/Documentation/userspace-api/media/v4l/selection-api-configuration.rst
@@ -135,3 +135,26 @@ and the height of rectangles obtained using ``V4L2_SEL_TGT_CROP`` and
 ``V4L2_SEL_TGT_COMPOSE`` targets. If these are not equal then the
 scaling is applied. The application can compute the scaling ratios using
 these values.
+
+Configuration of Region of Interest (ROI)
+=========================================
+
+The range of coordinates of the top left corner, width and height of
+areas that can be ROI is given by the ``V4L2_SEL_TGT_ROI_BOUNDS`` target.
+It is recommended for the driver developers to put the top/left corner
+at position ``(0,0)``. The rectangle's coordinates are in global sensor
+coordinates. The units are in pixels and independent of the field of view.
+They are not impacted by any cropping or scaling that is currently being
+used.
+
+The top left corner, width and height of the Region of Interest area
+currently being employed by the device is given by the
+``V4L2_SEL_TGT_ROI_CURRENT`` target. It uses the same coordinate system
+as ``V4L2_SEL_TGT_ROI_BOUNDS``.
+
+In order to change active ROI top left, width and height coordinates
+use ``V4L2_SEL_TGT_ROI`` target.
+
+Each capture device has a default ROI rectangle, given by the
+``V4L2_SEL_TGT_ROI_DEFAULT`` target. Drivers shall set the ROI rectangle
+to the default when the driver is first loaded, but not later.
diff --git a/Documentation/userspace-api/media/v4l/v4l2-selection-targets.rst b/Documentation/userspace-api/media/v4l/v4l2-selection-targets.rst
index e877ebbdb32e..cb3809418fa6 100644
--- a/Documentation/userspace-api/media/v4l/v4l2-selection-targets.rst
+++ b/Documentation/userspace-api/media/v4l/v4l2-selection-targets.rst
@@ -69,3 +69,24 @@ of the two interfaces they are used.
 	modified by hardware.
       - Yes
       - No
+    * - ``V4L2_SEL_TGT_ROI_CURRENT``
+      - 0x0200
+      - Current Region of Interest rectangle.
+      - Yes
+      - No
+    * - ``V4L2_SEL_TGT_ROI_DEFAULT``
+      - 0x0201
+      - Suggested Region of Interest rectangle.
+      - Yes
+      - No
+    * - ``V4L2_SEL_TGT_ROI_BOUNDS``
+      - 0x0202
+      - Bounds of the Region of Interest rectangle. All valid ROI rectangles fit
+	inside the ROI bounds rectangle.
+      - Yes
+      - No
+    * - ``V4L2_SEL_TGT_ROI``
+      - 0x0203
+      - Sets the new Region of Interest rectangle.
+      - Yes
+      - No
diff --git a/include/uapi/linux/v4l2-common.h b/include/uapi/linux/v4l2-common.h
index 7d21c1634b4d..d0c108fba638 100644
--- a/include/uapi/linux/v4l2-common.h
+++ b/include/uapi/linux/v4l2-common.h
@@ -78,6 +78,14 @@
 #define V4L2_SEL_TGT_COMPOSE_BOUNDS	0x0102
 /* Current composing area plus all padding pixels */
 #define V4L2_SEL_TGT_COMPOSE_PADDED	0x0103
+/* Current Region of Interest area */
+#define V4L2_SEL_TGT_ROI_CURRENT	0x0200
+/* Default Region of Interest area */
+#define V4L2_SEL_TGT_ROI_DEFAULT	0x0201
+/* Region of Interest bounds */
+#define V4L2_SEL_TGT_ROI_BOUNDS	0x0202
+/* Set Region of Interest area */
+#define V4L2_SEL_TGT_ROI		0x0203
 
 /* Selection flags */
 #define V4L2_SEL_FLAG_GE		(1 << 0)
-- 
2.30.0