diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst')
-rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst new file mode 100644 index 000000000..2d78b4f59 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst @@ -0,0 +1,125 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_SUBDEV_G_CROP: + +************************************************ +ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP +************************************************ + +Name +==== + +VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad + +Synopsis +======== + +.. c:macro:: VIDIOC_SUBDEV_G_CROP + +``int ioctl(int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp)`` + +.. c:macro:: VIDIOC_SUBDEV_S_CROP + +``int ioctl(int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``argp`` + Pointer to struct :c:type:`v4l2_subdev_crop`. + +Description +=========== + +.. note:: + + This is an :ref:`obsolete` interface and may be removed + in the future. It is superseded by + :ref:`the selection API <VIDIOC_SUBDEV_G_SELECTION>`. + +To retrieve the current crop rectangle applications set the ``pad`` +field of a struct :c:type:`v4l2_subdev_crop` to the +desired pad number as reported by the media API and the ``which`` field +to ``V4L2_SUBDEV_FORMAT_ACTIVE``. They then call the +``VIDIOC_SUBDEV_G_CROP`` ioctl with a pointer to this structure. The +driver fills the members of the ``rect`` field or returns ``EINVAL`` error +code if the input arguments are invalid, or if cropping is not supported +on the given pad. + +To change the current crop rectangle applications set both the ``pad`` +and ``which`` fields and all members of the ``rect`` field. They then +call the ``VIDIOC_SUBDEV_S_CROP`` 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 struct :c:type:`v4l2_subdev_crop` +contains the current format as would be returned by a +``VIDIOC_SUBDEV_G_CROP`` call. + +Applications can query the device capabilities by setting the ``which`` +to ``V4L2_SUBDEV_FORMAT_TRY``. 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. + +If the subdev device node has been registered in read-only mode, calls to +``VIDIOC_SUBDEV_S_CROP`` are only valid if the ``which`` field is set to +``V4L2_SUBDEV_FORMAT_TRY``, otherwise an error is returned and the errno +variable is set to ``-EPERM``. + +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. + +.. c:type:: v4l2_subdev_crop + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. flat-table:: struct v4l2_subdev_crop + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``pad`` + - Pad number as reported by the media framework. + * - __u32 + - ``which`` + - Crop rectangle to get or set, from enum + :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. + * - struct :c:type:`v4l2_rect` + - ``rect`` + - Crop rectangle boundaries, in pixels. + * - __u32 + - ``reserved``\ [8] + - Reserved for future extensions. Applications and drivers must set + the array to zero. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EBUSY + 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 + ``VIDIOC_SUBDEV_S_CROP`` + +EINVAL + The struct :c:type:`v4l2_subdev_crop` ``pad`` + references a non-existing pad, the ``which`` field references a + non-existing format, or cropping is not supported on the given + subdev pad. + +EPERM + The ``VIDIOC_SUBDEV_S_CROP`` ioctl has been called on a read-only subdevice + and the ``which`` field is set to ``V4L2_SUBDEV_FORMAT_ACTIVE``. |