[PATCH 1/2] v4l: Define a pixel format for the R-Car VSP1 2-D histogram engine

Niklas Söderlund
2016-09-02T14:09:59Z

The format is used on the R-Car VSP1 video queues that carry
2-D histogram statistics data.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
Documentation/media/uapi/v4l/meta-formats.rst | 1 +
.../media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst | 150 +++++++++++++++++++++
drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
include/uapi/linux/videodev2.h | 3 +-
4 files changed, 154 insertions(+), 1 deletion(-)
create mode 100644 Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst

diff --git a/Documentation/media/uapi/v4l/meta-formats.rst b/Documentation/media/uapi/v4l/meta-formats.rst
index 05ab91e..01e24e3 100644
--- a/Documentation/media/uapi/v4l/meta-formats.rst
+++ b/Documentation/media/uapi/v4l/meta-formats.rst
@@ -13,3 +13,4 @@ These formats are used for the :ref:`metadata` interface only.
:maxdepth: 1

pixfmt-meta-vsp1-hgo
+ pixfmt-meta-vsp1-hgt
diff --git a/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst b/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst
new file mode 100644
index 0000000..a093f0a
--- /dev/null
+++ b/Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst
@@ -0,0 +1,150 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _v4l2-meta-fmt-vsp1-hgt:
+
+*******************************
+V4L2_META_FMT_VSP1_HGT ('VSPT')
+*******************************
+
+*man V4L2_META_FMT_VSP1_HGT(2)*
+
+Renesas R-Car VSP1 2-D Histogram Data
+
+
+Description
+===========
+
+This format describes histogram data generated by the Renesas R-Car VSP1
+2-D Histogram (HGT) engine.
+
+The VSP1 HGT is a histogram computation engine that operates on HSV
+data. It operates on a possibly cropped and subsampled input image and
+computes the sum, maximum and minimum of the S component as well as a
+weighted frequency histogram based on the H and S components.
+
+The histogram is a matrix of 6 Hue and 32 Saturation buckets, 192 in
+total. Each HSV value is added to one or more buckets with a wight
+between 1 and 16 depending on how the Hue areas are setup. Finding the
+correct buckets is done by inspecting the H and S value independently.
+
+The Saturation position **n** (0 - 31) in the matrix are found by the
+expression:
+
+ 8 * n <= S < 8 * (n + 1)
+
+The Hue positions **m** (0 - 5) in the matrix depends on how the HGT Hue
+areas are configured. There are 6 user configurable Hue Areas which can
+be configured to cover overlapping Hue values:
+
+::
+
+ Area 0 Area 1 Area 2 Area 3 Area 4 Area 5
+ ________ ________ ________ ________ ________ ________
+ \ /| |\ /| |\ /| |\ /| |\ /| |\ /| |\ /
+ \ / | | \ / | | \ / | | \ / | | \ / | | \ / | | \ /
+ X | | X | | X | | X | | X | | X | | X
+ / \ | | / \ | | / \ | | / \ | | / \ | | / \ | | / \
+ / \| |/ \| |/ \| |/ \| |/ \| |/ \| |/ \
+ 5U 0L 0U 1L 1U 2L 2U 3L 3U 4L 4U 5L 5U 0L
+ <0..............................Hue Value............................255>
+
+As shown in the diagram a single Hue vale can be attributed to more then
+one Hue area. In such case the Hue value is attributed to both Hue
+Areas, but with a weight. The maximum weight is 16 and is associated
+with all Hue values that are inside the center of a Hue area (between nL
+-- nU). Values outside this area are weighted with a rounded down value
+along the diagonal line. If there is no overlapped areas specified the
+value is included in the lower area.
+
+The Hue area setup must match one of the following constrains:
+
+::
+
+ 0L <= 0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U
+
+::
+
+ 0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U <= 0L
+
+**Byte Order.**
+All data is stored in memory in little endian format. Each cell in the tables
+contains one byte.
+
+.. flat-table:: VSP1 HGT Data - (800 bytes)
+ :header-rows: 2
+ :stub-columns: 0
+
+ * - Offset
+ - :cspan:`4` Memory
+ * -
+ - [31:24]
+ - [23:16]
+ - [15:8]
+ - [7:0]
+ * - 0
+ - -
+ - S max [7:0]
+ - -
+ - S min [7:0]
+ * - 4
+ - :cspan:`4` S sum [31:0]
+ * - 8
+ - -
+ - Hue Area 0 Lower Boundary (0L) [0:7]
+ - -
+ - Hue Area 0 Upper Boundary (0U) [0:7]
+ * - 12
+ - -
+ - Hue Area 1 Lower Boundary (1L) [0:7]
+ - -
+ - Hue Area 1 Upper Boundary (1U) [0:7]
+ * - 16
+ - -
+ - Hue Area 2 Lower Boundary (2L) [0:7]
+ - -
+ - Hue Area 2 Upper Boundary (2U) [0:7]
+ * - 20
+ - -
+ - Hue Area 3 Lower Boundary (3L) [0:7]
+ - -
+ - Hue Area 3 Upper Boundary (3U) [0:7]
+ * - 24
+ - -
+ - Hue Area 4 Lower Boundary (4L) [0:7]
+ - -
+ - Hue Area 4 Upper Boundary (4U) [0:7]
+ * - 28
+ - -
+ - Hue Area 5 Lower Boundary (5L) [0:7]
+ - -
+ - Hue Area 5 Upper Boundary (5U) [0:7]
+ * - 32
+ - :cspan:`4` Histogram bucket (m=0, n=0) [31:0]
+ * - 36
+ - :cspan:`4` Histogram bucket (m=0, n=1) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 156
+ - :cspan:`4` Histogram bucket (m=0, n=31) [31:0]
+ * - 160
+ - :cspan:`4` Histogram bucket (m=1, n=0) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 288
+ - :cspan:`4` Histogram bucket (m=2, n=0) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 416
+ - :cspan:`4` Histogram bucket (m=3, n=0) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 544
+ - :cspan:`4` Histogram bucket (m=4, n=0) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 672
+ - :cspan:`4` Histogram bucket (m=5, n=0) [31:0]
+ * -
+ - :cspan:`4` ...
+ * - 796
+ - :cspan:`4` Histogram bucket (m=5, n=31) [31:0]
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index b7f7d5f..f459c4f 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1259,6 +1259,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
case V4L2_SDR_FMT_CS14LE: descr = "Complex S14LE"; break;
case V4L2_SDR_FMT_RU12LE: descr = "Real U12LE"; break;
case V4L2_META_FMT_VSP1_HGO: descr = "R-Car VSP1 1-D Histogram"; break;
+ case V4L2_META_FMT_VSP1_HGT: descr = "R-Car VSP1 2-D Histogram"; break;

default:
/* Compressed formats */
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 1dbe52a..c8c046c 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -638,7 +638,8 @@ struct v4l2_pix_format {
#define V4L2_SDR_FMT_RU12LE v4l2_fourcc('R', 'U', '1', '2') /* real u12le */

/* Meta-data formats */
-#define V4L2_META_FMT_VSP1_HGO v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 Histogram */
+#define V4L2_META_FMT_VSP1_HGO v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 1-D Histogram */
+#define V4L2_META_FMT_VSP1_HGT v4l2_fourcc('V', 'S', 'P', 'T') /* R-Car VSP1 2-D Histogram */

/* priv field value to indicates that subsequent fields are valid. */
#define V4L2_PIX_FMT_PRIV_MAGIC 0xfeedcafe
--
2.9.3