Documentation/userspace-api/media/v4l/vidioc-prepare-buf.rst
Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/v4l/vidioc-prepare-buf.rst
File Facts
- System
- Linux kernel
- Corpus path
Documentation/userspace-api/media/v4l/vidioc-prepare-buf.rst- Extension
.rst- Size
- 1371 bytes
- Lines
- 57
- Domain
- Support Tooling And Documentation
- Bucket
- Documentation
- Inferred role
- Support Tooling And Documentation: documentation
- Status
- atlas-only
Why This File Exists
Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
- Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
- Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.
Dependency Surface
- No C-style include directives detected by the generator.
Detected Declarations
- No top-level syscall, struct, function, initcall, or export declaration detected by the generator.
Annotated Snippet
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L
.. _VIDIOC_PREPARE_BUF:
************************
ioctl VIDIOC_PREPARE_BUF
************************
Name
====
VIDIOC_PREPARE_BUF - Prepare a buffer for I/O
Synopsis
========
.. c:macro:: VIDIOC_PREPARE_BUF
``int ioctl(int fd, VIDIOC_PREPARE_BUF, struct v4l2_buffer *argp)``
Arguments
=========
``fd``
File descriptor returned by :c:func:`open()`.
``argp``
Pointer to struct :c:type:`v4l2_buffer`.
Description
===========
Applications can optionally call the :ref:`VIDIOC_PREPARE_BUF` ioctl to
pass ownership of the buffer to the driver before actually enqueuing it,
using the :ref:`VIDIOC_QBUF <VIDIOC_QBUF>` ioctl, and to prepare it for future I/O. Such
preparations may include cache invalidation or cleaning. Performing them
in advance saves time during the actual I/O.
The struct :c:type:`v4l2_buffer` structure is specified in
:ref:`buffer`.
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
File I/O is in progress.
EINVAL
The buffer ``type`` is not supported, or the ``index`` is out of
bounds, or no buffers have been allocated yet, or the ``userptr`` or
``length`` are invalid.Annotation
- Atlas domain: Support Tooling And Documentation / Documentation.
- Implementation status: atlas-only.
Implementation Notes
- This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
- Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
- Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.