[PATCH 7/7] media: v4l: Support line-based metadata capture

Sakari Ailus
2023-06-30T20:44:01Z

many camera sensors, among other devices, transmit embedded data and image
data for each CSI-2 frame. This embedded data typically contains register
configuration of the sensor that has been used to capture the image data
of the same frame.

The embedded data is received by the CSI-2 receiver and has the same
properties as the image data, including that it is line based: it has
width, height and bytesperline (stride).

Add these fields to struct v4l2_meta_format and document them.

Also add V4L2_FMT_FLAG_META_LINE_BASED to tell a given format is
line-based i.e. these fields of struct v4l2_meta_format are valid for it.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
.../userspace-api/media/v4l/dev-meta.rst | 15 +++++++++++++++
.../userspace-api/media/v4l/vidioc-enum-fmt.rst | 7 +++++++
.../media/videodev2.h.rst.exceptions | 1 +
drivers/media/v4l2-core/v4l2-ioctl.c | 5 +++--
include/uapi/linux/videodev2.h | 10 ++++++++++
5 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/Documentation/userspace-api/media/v4l/dev-meta.rst b/Documentation/userspace-api/media/v4l/dev-meta.rst
index 0e7e1ee1471a..4b24bae6e171 100644
--- a/Documentation/userspace-api/media/v4l/dev-meta.rst
+++ b/Documentation/userspace-api/media/v4l/dev-meta.rst
@@ -65,3 +65,18 @@ to 0.
- ``buffersize``
- Maximum buffer size in bytes required for data. The value is set by the
driver.
+ * - __u32
+ - ``width``
+ - Width of a line of metadata in samples. Valid when :c:type`v4l2_fmtdesc`
+ flag ``V4L2_FMT_FLAG_META_LINE_BASED`` is set, otherwise zero. See
+ :c:func:`VIDIOC_ENUM_FMT`.
+ * - __u32
+ - ``height``
+ - Number of rows of metadata. Valid when :c:type`v4l2_fmtdesc` flag
+ ``V4L2_FMT_FLAG_META_LINE_BASED`` is set, otherwise zero. See
+ :c:func:`VIDIOC_ENUM_FMT`.
+ * - __u32
+ - ``bytesperline``
+ - Offset in bytes between the beginning of two consecutive lines. Valid
+ when :c:type`v4l2_fmtdesc` flag ``V4L2_FMT_FLAG_META_LINE_BASED`` is
+ set, otherwise zero. See :c:func:`VIDIOC_ENUM_FMT`.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
index 000c154b0f98..6d7664345a4e 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
@@ -227,6 +227,13 @@ the ``mbus_code`` field is handled differently:
The application can ask to configure the quantization of the capture
device when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with
:ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.
+ * - ``V4L2_FMT_FLAG_META_LINE_BASED``
+ - 0x0200
+ - The metadata format is line-based. In this case the ``width``,
+ ``height`` and ``bytesperline`` fields of :c:type:`v4l2_meta_format` are
+ valid. The buffer consists of ``height`` lines, each having ``width``
+ bytes of data and offset between the beginning of each two consecutive
+ lines is ``bytesperline``.

Return Value
============
diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
index 2a589d34b80e..5d623bf03bc5 100644
--- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
+++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
@@ -211,6 +211,7 @@ replace define V4L2_FMT_FLAG_CSC_XFER_FUNC fmtdesc-flags
replace define V4L2_FMT_FLAG_CSC_YCBCR_ENC fmtdesc-flags
replace define V4L2_FMT_FLAG_CSC_HSV_ENC fmtdesc-flags
replace define V4L2_FMT_FLAG_CSC_QUANTIZATION fmtdesc-flags
+replace define V4L2_FMT_FLAG_META_LINE_BASED fmtdesc-flags

# V4L2 timecode types
replace define V4L2_TC_TYPE_24FPS timecode-type
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 7781b0bd3e7d..2c7a7a6059cc 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -343,8 +343,9 @@ static void v4l_print_format(const void *arg, bool write_only)
case V4L2_BUF_TYPE_META_OUTPUT:
meta = &p->fmt.meta;
pixelformat = meta->dataformat;
- pr_cont(", dataformat=%p4cc, buffersize=%u\n",
- &pixelformat, meta->buffersize);
+ pr_cont(", dataformat=%p4cc, buffersize=%u, width=%u, height=%u, bytesperline=%u\n",
+ &pixelformat, meta->buffersize, meta->width,
+ meta->height, meta->bytesperline);
break;
}
}
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 13d404699842..7485920f1ac9 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -873,6 +873,7 @@ struct v4l2_fmtdesc {
#define V4L2_FMT_FLAG_CSC_YCBCR_ENC 0x0080
#define V4L2_FMT_FLAG_CSC_HSV_ENC V4L2_FMT_FLAG_CSC_YCBCR_ENC
#define V4L2_FMT_FLAG_CSC_QUANTIZATION 0x0100
+#define V4L2_FMT_FLAG_META_LINE_BASED 0x0200

/* Frame Size and frame rate enumeration */
/*
@@ -2407,10 +2408,19 @@ struct v4l2_sdr_format {
* struct v4l2_meta_format - metadata format definition
* @dataformat: little endian four character code (fourcc)
* @buffersize: maximum size in bytes required for data
+ * @width: number of bytes of data per line (valid for line based
+ * formats only, see format documentation)
+ * @height: number of lines of data per buffer (valid for line based
+ * formats only)
+ * @bytesperline: offset between the beginnings of two adjacent lines in
+ * bytes (valid for line based formats only)
*/
struct v4l2_meta_format {
__u32 dataformat;
__u32 buffersize;
+ __u32 width;
+ __u32 height;
+ __u32 bytesperline;
} __attribute__ ((packed));

/**
--
2.39.2