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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-04 06:59:38 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-04 06:59:38 +0300 |
commit | a98f670e41a99f53acb1fb33cee9c6abbb2e6f23 (patch) | |
tree | f8ae10a4cb91758ad7f9422053753a8c5d0f04dc /Documentation/userspace-api/media/v4l/vidioc-g-crop.rst | |
parent | ee01c4d72adffb7d424535adf630f2955748fa8b (diff) | |
parent | 938b29db3aa9c293c7c1366b16e55e308f1a1ddd (diff) | |
download | linux-a98f670e41a99f53acb1fb33cee9c6abbb2e6f23.tar.xz |
Merge tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab:
- Media documentation is now split into admin-guide, driver-api and
userspace-api books (a longstanding request from Jon);
- The media Kconfig was reorganized, in order to make easier to select
drivers and their dependencies;
- The testing drivers now has a separate directory;
- added a new driver for Rockchip Video Decoder IP;
- The atomisp staging driver was resurrected. It is meant to work with
4 generations of cameras on Atom-based laptops, tablets and cell
phones. So, it seems worth investing time to cleanup this driver and
making it in good shape.
- Added some V4L2 core ancillary routines to help with h264 codecs;
- Added an ov2740 image sensor driver;
- The si2157 gained support for Analog TV, which, in turn, added
support for some cx231xx and cx23885 boards to also support analog
standards;
- Added some V4L2 controls (V4L2_CID_CAMERA_ORIENTATION and
V4L2_CID_CAMERA_SENSOR_ROTATION) to help identifying where the camera
is located at the device;
- VIDIOC_ENUM_FMT was extended to support MC-centric devices;
- Lots of drivers improvements and cleanups.
* tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (503 commits)
media: Documentation: media: Refer to mbus format documentation from CSI-2 docs
media: s5k5baf: Replace zero-length array with flexible-array
media: i2c: imx219: Drop <linux/clk-provider.h> and <linux/clkdev.h>
media: i2c: Add ov2740 image sensor driver
media: ov8856: Implement sensor module revision identification
media: ov8856: Add devicetree support
media: dt-bindings: ov8856: Document YAML bindings
media: dvb-usb: Add Cinergy S2 PCIe Dual Port support
media: dvbdev: Fix tuner->demod media controller link
media: dt-bindings: phy: phy-rockchip-dphy-rx0: move rockchip dphy rx0 bindings out of staging
media: staging: dt-bindings: phy-rockchip-dphy-rx0: remove non-used reg property
media: atomisp: unify the version for isp2401 a0 and b0 versions
media: atomisp: update TODO with the current data
media: atomisp: adjust some code at sh_css that could be broken
media: atomisp: don't produce errs for ignored IRQs
media: atomisp: print IRQ when debugging
media: atomisp: isp_mmu: don't use kmem_cache
media: atomisp: add a notice about possible leak resources
media: atomisp: disable the dynamic and reserved pools
media: atomisp: turn on camera before setting it
...
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-g-crop.rst')
-rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-g-crop.rst | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-crop.rst b/Documentation/userspace-api/media/v4l/vidioc-g-crop.rst new file mode 100644 index 000000000000..10e086be55d5 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-g-crop.rst @@ -0,0 +1,119 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + +.. _VIDIOC_G_CROP: + +********************************** +ioctl VIDIOC_G_CROP, VIDIOC_S_CROP +********************************** + +Name +==== + +VIDIOC_G_CROP - VIDIOC_S_CROP - Get or set the current cropping rectangle + + +Synopsis +======== + +.. c:function:: int ioctl( int fd, VIDIOC_G_CROP, struct v4l2_crop *argp ) + :name: VIDIOC_G_CROP + +.. c:function:: int ioctl( int fd, VIDIOC_S_CROP, const struct v4l2_crop *argp ) + :name: VIDIOC_S_CROP + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``argp`` + Pointer to struct :c:type:`v4l2_crop`. + + +Description +=========== + +To query the cropping rectangle size and position applications set the +``type`` field of a struct :c:type:`v4l2_crop` structure to the +respective buffer (stream) type and call the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` ioctl +with a pointer to this structure. The driver fills the rest of the +structure or returns the ``EINVAL`` error code if cropping is not supported. + +To change the cropping rectangle applications initialize the ``type`` +and struct :c:type:`v4l2_rect` substructure named ``c`` of a +v4l2_crop structure and call the :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctl with a pointer +to this structure. + +The driver first adjusts the requested dimensions against hardware +limits, i. e. the bounds given by the capture/output window, and it +rounds to the closest possible values of horizontal and vertical offset, +width and height. In particular the driver must round the vertical +offset of the cropping rectangle to frame lines modulo two, such that +the field order cannot be confused. + +Second the driver adjusts the image size (the opposite rectangle of the +scaling process, source or target depending on the data direction) to +the closest size possible while maintaining the current horizontal and +vertical scaling factor. + +Finally the driver programs the hardware with the actual cropping and +image parameters. :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` is a write-only ioctl, it does not +return the actual parameters. To query them applications must call +:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_G_FMT`. When the +parameters are unsuitable the application may modify the cropping or +image parameters and repeat the cycle until satisfactory parameters have +been negotiated. + +When cropping is not supported then no parameters are changed and +:ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` returns the ``EINVAL`` error code. + + +.. c:type:: v4l2_crop + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. flat-table:: struct v4l2_crop + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``type`` + - Type of the data stream, set by the application. Only these types + are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``, ``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``, + ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`` and + ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :c:type:`v4l2_buf_type` and the note below. + * - struct :c:type:`v4l2_rect` + - ``c`` + - Cropping rectangle. The same co-ordinate system as for struct + :c:type:`v4l2_cropcap` ``bounds`` is used. + +.. note:: + Unfortunately in the case of multiplanar buffer types + (``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE``) + this API was messed up with regards to how the :c:type:`v4l2_crop` ``type`` field + should be filled in. Some drivers only accepted the ``_MPLANE`` buffer type while + other drivers only accepted a non-multiplanar buffer type (i.e. without the + ``_MPLANE`` at the end). + + Starting with kernel 4.13 both variations are allowed. + + +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. + +ENODATA + Cropping is not supported for this input or output. |